This is the complete review of the Mutt4gery rifle I have built.  It is split up into 2 sections, INDIVIDUAL PARTS and RANGE REPORT.  At the end is accuracy results.



No, the rifles are not bent, that is my lovely camera.

INDIVIDUAL PARTS:

2003 FAB-10 Lower Receiver-  This is an AR-15 lower with a fixed 10-round magazine to make it CA-legal.  The finish on this part is very nice and durable.  None of the holes had to be deburred for installation of a lower parts kit.  Those are about the only three things it has going for it.  It is lacking an area to install the bolt catch, where instead it has a hole for a (rather poorly constructed) stripper clip guide.  The integrated magazine is a cut 30 round LE magazine.  The body itself is fine.  The spring is also cut down from a 30 rounder, I found it to be a little on the weak side.  The follower is a USGI GF with the anti-tilt legs cut off so that it can't be modified to hold more than 10 rounds.  This is not necessary as it would be perfectly legal to allow it to hold 10 rounds with the anti-tilt legs.  It would be illegal to modify it to hold more than 10 rounds.  The spring/follower combination has been a source of problems, see the range report below for details.  Another, problem is the buffer retainer hole is drilled about a half milimeter further to the rear than it should be.  When the buffer tube was in it's final, correct position, it would contact the post of the buffer retainer in such a way as to create significant resistance to the buffer retainer's movement up/down in it's hole in addition to depressing the retainer slightly beyond regulation.  I had to shave off a _VERY SMALL_ portion of the buffer tube to allow the buffer retainer to move up/down in it's hole, details here: www.ar15.com/forums/topic.html?b=3&f=4&t=168534.  For such an expensive part ($300+), I expect better QC.

Note: Originally I was unsure if this was a problem with the buffer tube or the lower, I have since concluded with 99% positivity that it is indeed a problem with the lower.

2003 ShoeLess Ventures Stainless Grenade Pullring-style takedown pin-  If you can find someone to make one for you, I'd go that route.  I didn't really like the quality of the pullring-takedown pin ShoeLess sent me.  There's nothing really functionally wrong, and on the outside it's cosmetically fine.  It's the inside where there are little pits on the shaft.  The detent slot is fine and smooth though.  It just bothers me because this tiny part was $20.  For 1/3 the cost of a Bushmaster lower parts kit I expect better quality than provided.

2003 RRA 6-position unmarked stock- Fit and finish are great, I've had no problems with it.  It's gone largely unnoticed during range firing.  Which is a good thing, because if I'm noticing something, it's probably a problem.  The rubber butt pad I put on it is very nice as well.  It absorbs a bit of recoil and creates an arc which fits well into the "pocket" of my shoulder.

2003 Bushmaster Lower Parts kit - Wonderful.  No problem whatsoever.  The trigger is very smooth, not the least bit of hiccup during pull and has just the amount of pull I like (feels like 5-7lbs).  I think I might have lucked out and received one of the better kits.

2003 ARMS #40A2- Fits great, functions flawlessly.  I am definetly glad I went with the A2 version, I can't imagine how difficult and annoying it would be to not have a full aperature on the 600m aperature.  I have not attempted to detach and reattach it to see it's re-zeroing capabilities, but as far as flipping it up and down repeatedly it always pops up to zero perfectly.

2003 CMMG/DPMS 16" Pre-Ban Upper Receiver Assembly, incl Barrel- Nicely constructed with top-line materials.  Upper receiver is an Anchor Harvey forging, barrel is 4150 steel.  Mine came with an O-ring already installed on the extractor spring which I have removed.  It is not without it's problems however.  The front site tower is cast, which is the only thing that keeps this upper from being mil-spec.  Not a big deal.  However, the front site post is not entirely flat on top, it is sloped slightly.  This is somewhat annoying when trying aim.  The front sight was also quite stuck and required generous amounts of CLP to get it to move.  Even now it's extremely stiff and difficult to adjust.  The tower itself is off center, as I had to set the windage on my ARMS #40A2 around 15 clicks to the right.  The A2 flash hider was also improperly indexed almost 90 degrees from where it should be.  I managed to re-index it closer to what it should be, but I am still waiting on peel washers (free from CMMG) to get it entirely correct.  I have also had repeated failures to extract due to a tight/rough chamber which I have been able to fix or atleast lessen, detailed in the range report below.

Note:  Overall fit between the upper and the lower is extremely tight.  It is almost impossible to pull the takedown pin, even with the grenade-style ring.  I repeatedly found myself using a punch, it has loosened up a bit since and can be pulled with some effort.

RANGE REPORT:

For the entire duration of tests the O-ring has been removed from the extractor spring.  An AR-15 should be 99% reliable without it, and the O-ring should be the extra oomph.  I do not want a rifle that is 50% reliable and is fixed by an O-ring.  Until I can see the wear marks on this rifle (and thus know the good lube points), I have kept the lower and upper [u]swimming[/u] in CLP.  Note there is no CLP in the bore, only the locking lugs.  I have taken this rifle out to the range 3 times with 5 "different" types of ammunition.

*Federal/Lake City XM193 Lot 19 (XM193L19)
*Winchester Q3131 (WQ3131)
*South African .223 Lot 009 by Denel (Pty) Ltd. (SA223L009)
Federal/Lake City XM193 Lot 27 (XM193L27)
Winchester Q3131A (WQ3131A)

* = These were purchased from a shop with no air conditioning, the temperature sway in that place is incredible, not a good place to store ammunition.

[u]Day 1, Saturday, ~100F degrees, ~1000ft, moderate humidity, 5mph wind[/u]
Ammunition used:  XM193L19, WQ3131, XM193L27, WQ3131A
Total rounds fired: 70

As impatient as I was to find out what kind of groups this thing would shoot, I wanted to do a barrel break-in first.  I did 10 rounds of 1-shot, 1-clean.  I did not take it any further as I am not 100% convinced as to the benefits of a barrel break-in, but it makes sense on paper.  I will not loose sleep over not going onto 2shot, 3shot, 5shot, etc.  Cleaning cycle of the break-in period consisted of 1 patch Hoppies #9, 1 dry patch, 1 patch Barnes CR-10 (awesome copper solvent), waiting about 2 minutes, then 2 dry patches.  When the entire break in was finished, I used patches of Hoppies #9+dry and Break Free CLP+dry to clean out the barrel thuroughly before continuing.  I had planned to chronograph all shots fired, document them and report averages.  I also wanted to see how this upper would do as far as accuracy.  I took chronograph figures throughout the cleaning cycle, but after being directly under the sun and hot for about 3 hours, I took the chronograph down and decided to hold off on trying to shoot nice groups.  I spent the remainder of the time generally-zeroing my rifle and shooting as fast as possible to test reliability.  The front sight post was stuck firmly in place and was a REAL PAIN to adjust even after generous amounts of CLP.  Every time the magazine would get down to 2-3 rounds, I would have a bolt-over bullet FTF.  Pulling back the bolt revealed a magazine that had the rear of the follower sticking down.  I also had 2 FTEx with the XM193.  All these required was for me to close the bolt on them and pull the charging handle back.  It extracted and ejected them fine.  The extractor was chewing up the rims of the brass pretty well and there appeared to be friction marks on the sides of the casing.  The carbine buffer was showing some [b]slight[/b] marking/denting around it's edge.  When all was said and done I was very sunburned (peeling now) and had been out in the sun for 6 hours.

Chrono numbers, 4 shot average (remember this stuff was poorly stored):

WQ3131:   3071fps
XM193L19: 3112fps

Conclusions:  I could not come to any conclusions about the buffer yet because it looked like fairly normal marking, that I would expect.  I decided to not worry about this until I got more rounds through the rifle.  I was unsure as to what caused the 2 FTEx's and they were not my immediate concern.  I left my options open as to what was causing them and did little research, basically got the ball rolling [url]http://www.ar15.com/forums/topic.html?b=3&f=66&t=169185[/url].  All I did for the 2nd time out was clean the CLP off the bolt face and extractor catch, incase it was due to extractor slippage.  The magazine stoppages were constant and annoying, they were my first priority to fix.  I used a C-clamp to to compress the spring/follower into the magazine and cleaned the inside of it with 100% alcohol.  I then lubed it with dry graphite like locksmith's use in locks.  I do not particularly like this as this stuff is kind of dirty and gets shot up into the CLP covered bolt carrier, etc.  I will search for alternates later, I've heard Lumpy say something about Molysomething that I think is dry and lubes well *shrug*.

[u]Day 2, Tuesday, ~90F degrees, ~1000ft, moderate humidity, 0 wind[/u]
Ammunition used:  WQ3131, WQ3131A, XM193L27, SA223L009
Total rounds fired: 28

The graphite lube tended to work relatively well.  It seemed to work better as it got worked-in to the magazine more.  This trip was cut short however due to FTEx's.  I had been firing WQ3131, WQ3131A and SA223L009 without a problem.  I loaded 4 rounds of XM193 and had an FTEx on the first.  The bolt had stripped another off the magazine and shoved it into the empty round in the chamber.  The bullet was jammed back into the case so far I could only see a few milimeters of the tip.  After clearing this jam, all that was required was the bolt to be closed over the case and have the charging handle pulled back.  So I tried the XM193 again, same problem, same solution, only difference was the round stripped off the magazine afterward showed no damage.  I tried the 4th round, no problem.  So I loaded up a few rounds of the SA223L009.  First round, FTEx.  Closing the bolt over the casing and pulling the charging handle did not work, I had to cut the day short.  I tapped the round out with a cleaning rod.

Conclusions:  With the magazine performing better, if not perfect and the FTEx's becoming more prominent, the FTEx's became first priority.  An FAQ on the Bushmaster site, along with other readings from these forums and sites led me to believe it was either a Tight/Rough Chamber or too much gas.  Too much gas seemed unlikely as there were no other problems associated with too much gas.  The extractor was deforming the rims of the cases badly which told me that the extractor was holding on just fine and that there was significant resistance against being removed from the chamber.  Placing the O-ring back on might make it hold even better and might have prevented some of the FTEx's.  However, the extractor should not have to work that hard in the first place and this would put undue excessive stress on the extractor.  Not to mention this could dangerously rip the entire rim off the bottom of a case and make it impossible to tap out with a cleaning rod.  I talked to CMMG and they recommended I use a drill and a chamber brush to polish the chamber for about 30 seconds.  I coated the chamber brush in CLP and gave the drill a whirl in the chamber for about 15 seconds.  I ran a couple patches down the barrel, cleaned/relubed the carrier, bolt and upper.  Buffer was still being marked, but 28 rounds didn't make much difference or give me enough information to make a conclusion.

[u]Day 3, Wednesday, ~85F degrees, ~1000ft, high humidity, 0 wind[/u]
Ammunition used:  WQ3131A, XM193L27, SA223L009
Total rounds fired: 70

All of the first 62 rounds went flawlessly.  Markings on the case rim were very light to moderate.  No failures to extract.  The final 8 rounds I dropped into some talcum powder-like dust and loaded them into the magazine.  All of them fired, extracted, and ejected except for 3.  2 of them extracted but did not eject (and thus created a stove-pipe).  My guess is the extractor was strong enough to pull them out but just barely.  It let them loose early and the ejector was not able to get a good punch on them.  The O-ring would fix this.  The 7th round failed to extract and needed to be tapped out as the rim was completely devastated.  All 8 of these rounds had severe case rim damage due to extra resistance during extraction.  The day was cut off by rain and lack of ammunition.  During this time, I figured out exactly what was happening with the magazine.

Conclusions:
Magazine- By the 3rd trip out the magazine was functioning properly, except when I had to initially pull the bolt back to chamber the first round (remember, no bolt catch).  The bolt would hit the rear of the round on it's way back and tilt it downward.  The neck of the adjacent round (the round underneath it) would roll outward and catch on the top of those little line-indents that re-enforce the magazine.  The spring is not strong enough to force the rear of the follower back up when only 2-5 rounds are loaded/remaining.  During normal firing, the vibration, etc. was enough that with the graphite lubricant applied and worked in, it had no problems or stoppages.  I just had to make sure when I loaded a new magazine with only 2-5 rounds and pulled the bolt back I pushed the neck of the round back down to make the rear pop back up.  I plan to shave/smooth/lubricate the edges where the neck is getting caught and replace the spring with a cut down 30rd Wolff Extra power spring.  There is _almost_ room for an 11th round, so I plan to cut a new follower and leave the anti-tilt posts slightly longer for better feeding.

Upper- Seems [b]much[/b] better.  I think I will polish it for another 15 seconds with the drill, then put 200 rounds through it in one sitting.  I was somewhat impressed with it's ability to eat dirty ammunition.  I don't think it would've eaten a single one of those originally.  CMMG/DPMS has vowed to stand behind their product and I am positive they will, I will be keeping in touch with them.

Buffer-  The marks and [b]small[/b] dents around the edge of the buffer are still minor.  Originally I thought it might be a sharp edge on the bolt carrier but now I am almost positive it's due to the buffer retainer being impacted.  Remember, the buffer retainer is a little more reward than it should be.  Nevertheless, the bolt carrier is still resting against the buffer when closed (I CLP'd the buffer and wiped the rear of the carrier dry to find out), but probably just barely.  The buffer retainer is in fine condition.  With how little the buffer retainer hole is off to the rear, it shouldn't create a significant problem.  The buffer should wear slightly around the edge and then stop as it will come to rest more against the bolt carrier rather than the retainer.  I will keep an eye on it.  If the wear makes the buffer too light (unlikely with how very little it is worn) I'll switch to an H-buffer.  Trading in my lower for another would be a huge PITA with CA's gun registry and DROS fees.  Additionally, there is no guarantee that the replacement wouldn't have a more significant flaw.


ACCURACY:

I was impressed by the accuracy of this rifle.  All shooting took place at [b]50 yards using iron sights[/b] (ARMS #40A2 rear).  I am convinced if I had an optic I could've made one enlarged .223 hole with this military ammunition.  I wonder what this thing will do with match ammunition and/or an optic!

Off hand I could easily place all shots quickly into a 4"x4" square using WQ3131/WQ3131A or XM193.

From a bench rest, shooting quickly and not particularly concentrating, I could readily attain:
1-1.25" groups with WQ3131 and WQ3131A
1.25-1.75" groups with Federal/LC XM193

Concentrating and shooting the best I could from the bench yielded:
0.6" group with WQ3131A
1" group with Federal/LC XM193

All grid lines are 1" x 1"

XM193 typical group:
[img]http://www.mti-security.com/pics/ar15/tgts/xm193typ.jpg[/img]
WQ3131 typical group:
[img]http://www.mti-security.com/pics/ar15/tgts/q3131typ.jpg[/img]
XM193 best group:
[img]http://www.mti-security.com/pics/ar15/tgts/xm193aim.jpg[/img]
WQ3131A best group:
[img]http://www.mti-security.com/pics/ar15/tgts/q3131aaim.jpg[/img]

Thank you to anyone and everyone on the AR15.com forums who has helped me along.  Thank you to CMMG for advice and standing behind your products.  I will post updates about my rifle as they happen.  For now, I don't think I'll be able to do any shooting for awhile.

[b]COMMENTS AND INPUT ARE MUCH APPRECIATED![/b]

Three questions for you knowledgable people out there.

1.  How well will your upper feed, fire, extract and eject rounds with a light coat of dust/dirt on them?

2.  What is a good, dry lubricant for the inside of magazines?

3.  Have any of you with a CMMG/DPMS upper noticed marks/dents on your buffer?

Thank you.

Yes, I have.I'm also having FTE's but not as bad as you've had.I think it may be an out of spec DPMS upper and not our lowers.I emailed DPMS to see if it may be a fault on their end and I'm awaiting a response.

Your best bet is to contact CMMG, not DPMS unless they refer you to DPMS.  Also, I noticed the dents on your buffer in your other post.  Those are terrible, especially after only 100 rounds.  Mine are nowhere nearly as bad.  I'm hoping to get a response from AR15fan, Yojimbo, or some others as well.  Please keep in contact with me as to the developements of the issues with your upper.

I didn't contact CMMG only because I didn't buy it directly from them.I bought it second hand but it is one of their uppers and figured they probably wouldn't help me out since I wasn't the original owner.

How would the upper be causing "dents" on the buffer?

Tweak mentioned that if the threads on the upper are too long then the barrel sits too far forward and the bolt carrier sits too far forward and the rear of the carrier is not flush, or above, the rear of the upper.The takedown holes may also be mislocated.I know the rear takedown pin is a PIA to push out unless I use a punch.

wyv3rn,

Good job on the writeup!

Though it didn't hurt I think you cold have skipped the barrel break in procedure.  My break in was about 300 rounds of Q3131a with no cleaning...[:D]

It looks like you are taking the proper steps to diagnosing your problem.  I not sure if I could ad much to what we've already discussed off line and what you mentioned here.  I'd be very intrested to know if it is a tight chamber.  Keep us posted.

As for you other questions, I've only used a light coating of CLP for the inside of my mags.  Another product that might help you would be Remington Dri-lube.  You should be able to find it at any gun store.  IIRC, you should try to avoid any lubes with graphite in it.  Graphite is suppose to be bad to use on aluminum because it causes corrosion.  

I've never tried firing any bullets that were coated in fine dirt so I don't know how mine would under those conditions.  The closest I've come to that was using Wolf[BD] ammo...

As for markings on the buffer, I have some light scratches on my buffer which comes from contact of the bolt carriers bottom edge when closing the upper and lower together.  When I look closely at my buffer detent pin I can see that the buffer and pin are not in contact when the receivers are closed.  In fact as it's closing I can see the carrier push it back just a few mm's away from the detent pin.  

I'm sorry to see you're still having trouble and I hope you get all sorted out soon.  Definitely keep us posted.

I seriously doubt the upper is creating the dents on our buffers.  First let's analyze yours.  You have what appears to be rather heavy denting.  It's around the outside edge of the buffer.  It abruptly stops, then starts again.  As the weapon functions, the buffer rotates slightly around.  If the carrier was so set forward as to impact the buffer on it's way back, you'd expect more even denting, not individual tiny dents in a circle.  And you'd expect them around the entire length of the buffer.  The marks on your buffer are more consistent with hitting the buffer retaining pin.  Atleast that's the way it appears from the picture.  I can say with 99% positivity my teeny buffer dings are being caused by the buffer retainer.

1.  After the first 70 rounds, tiny, individual dings were around the outside edge of the buffer, but STOPPED on the left side of the buffer retainer post where the buffer had not yet rotated to it.  After firing more rounds, the buffer has made a complete rotation and there are now tiny individual dings around the buffer.

2.  I had to modify my buffer tube because either A) it was too long or B) the buffer retainer hole was a tiny bit too far back.  Knowing the reputation of RRA vs. ShoeLess Ventures I am positive it is the fault of the lower, not the buffer tube.

The dents on your buffer are much much more severe than mine, I'd look into getting that solved.  Mine are tiny and the dinging/denting appears to not have progressed any further.  The buffer is now resting against the carrier rather than the buffer retainer.  The outside of your buffer will continue to wear until the center of your buffer eventually rests against the carrier.  However your buffer appears that it has a ways to wear before it stops.  Check your buffer retainer, make sure it is decent condition.  If it were my rifle, I'd sand the outside edge of the buffer down (basically do what the repeated firing is doing without all the wear against your retainer) and make sure the rifle still functions with the now lighter buffer.  If not, I'd get an H buffer and sand/cut it's outside edge so that it would rest against the carrier.  Also, make sure the center of the buffer, which is now protruding from the outside edge doesn't fit INSIDE the carrier and isn't so close to the edge of the inside that it will just chew it up.  Then again, you're outside California and it's easier and cheaper for you to buy another lower than it is me.

AR15fan, could you confirm or deny that you have any denting on your buffer?  It would help a lot.  We all need to pool our information together.  Any other information or observations you have, that may even seem insignificant, could really help so please share them.

Thank you!  It took awhile. [:)]



Will do.



I don't want to use CLP because I don't want the inside of my mag to get gunked up over time.  I actually got the recommendation to use graphite from MICHAEL AT SHOELESS VENTURES!  I did some research and you are right, it will corrode aluminium!  I am going to clean it thuroughly tomorrow!  I AM FLAMING PISSED OFF ABOUT THIS, WHAT AN IDIOT!  HE DOESN'T EVEN KNOW WHAT IS HARMFUL TO HIS OWN PRODUCT! [pissed]

I actually ordered some stuff called Tef-Dri the other day, I figured I'd give it a try.  I'm really interested in that 2 part Brownell's lube that's permanent.  It's that Molybendium stuff mixed with what seems to be some kind of adhesive.  Seems it's really popular for trigger jobs... *shrug*



Someone has to have tried this before, I feel shunned (maybe because I'm in California) by the lack of responses or atleast attempted answers to my question.

Thank you for the response, encouragement, and information, it's greatly appreciated! [:)]

For anyone following this as a source for FAB-10 QC information, I received an e-mail from another person having the same problem I am.  So it appears it's not an isolated incident.  My Wolff 30 round +10% magazine spring is on the way.  I'll let everyone know if my recipie to cure the magazine problem works, which I am positive it will.  My plan:

1.  Higher power cut-down spring.
2.  Slightly less cut-down follower.
3.  Sand/polish the edges the neck of the cases are getting stuck on.
4.  Lube the entire magazine with dry lubricant.

I haven't had any of the lower/mag issues with any of my FAB's, that wasn't "my" fault.

wyv3rn,

I took my AR apart today to look it over and my carrier is definetly flush with the upper and when I close the upper/lower, the carrier DOES push the buffer back just enough that I can see it doesn't touch the buffer.This is really strange.I emailed the person I bought the upper from and they said they never had any wear on their buffer.They ran a Colt 9mm buffer in it.He did mention he had wear like mine in another lower and replaced the buffer with a heavy buffer and the problem went away.I may be out of CA but my lower is a preban so replacing it isn't an option since PWA is no longer around.I'm not sure how to tell if the lower is out of spec.

Upon further inspection I have found there is indeed some chipping of the finish on my buffer face. TYhis wear is new, the finish flakes are still there. It never occurred in many thousands of round with the original upper, but this new DPMS upper has resulted in noticable chipping of the gold colored anodized finsih on my buffer face in only 360 rounds.

This is definately unexpected. I wonder if the problem is self limiting? Buffers are cheap, at about $10.00 each, but i would prefer not to have to replce mine often.

So what is the common cause of a new upper marring the face of an existing buffer?

I sure wish DPMS would jump in here with any suggestions.I emailed them about 4 days ago but haven't heard back.I ordered a Colt heavy buffer to see if it helps any.The previous owner of my upper used a Colt 9mm buffer in his lower with 0 problems and no retainer marks whatsoever.If it is an out of spec lower, anyone know of a remedy for this?Mine is a preban so i can't just send it to the manufacturer.

To the guys getting buffer marks,

With the upper removed from the lower, are you able to push on the carrier and make it move forward?  Or is it tight and always flush with the back of the upper receiver?

When the upper and lower is together do you have any fore and aft play?

I'm just wondering if there are loose tolerances involved because the buffer should not be able to move forward once the carrier and upper is seated properly.  

Like I mentioned before when the receivers are pinned together the carrier should actually push the buffer back just enough so there's no contact with the retaining pin when the action cycles.  Very strange indeed...

I'm answering from memory here, but it is tight and flush with the back of the upper.  I don't remember being able to push the carrier any further once it's locked in.



None at all, the fit is extremely tight.



When I close my upper the carrier pushes the buffer just slightly away from the buffer retainer, it's still VERY close.

On friday I used some Mother's Mag and Aluminum Polish on a .40cal bore mop to polish the chamber.  I had used this stuff previously with Q-tips to do a trigger job on my Glock 22, worked great.  I rotated the mop on a couple lengths of rod by hand and made sure to polish it lightly.  Cleanup took some time and patience to get it out of the crevices.  When I was finished, I could shine a light into my chamber and see almost mirror-like reflections.  I thuroughly cleaned out the chamber  and surrounding areas with 100% alcohol, Hoppies #9 and BreakFree CLP.

Now it was out to the range to dump 140 rounds of XM193 (120) and Q3131A (20) through it!  First 100 rounds (95 XM193, 5 Q3131A) went through it with no hiccup whatsoever.  Case rim marking was light to moderate.  Then I applied the talcum-powder like dust to 15 rounds and fired them.  I had 1 failure to extract.  Closing the bolt over it and pulling the charging handle extracted and ejected it.  The force required to pull the charging handle back was minimal, where as before it required considerable force to extract/eject a stuck casing.  Case rim wear on the dirty rounds varied from very light to heavy.  I fired the remaining 25 rounds without a problem.  Case rim wear was very light to moderate.  As more rounds were put through it, the lighter the case rim markings seemed to get.  I can only guess this has to do with micro-grooves being worn in by the chambering/extracting of casings as opposed to micro-grooves created by the rotation of the .40cal brush with polish.

The buffer has no more noticeable marking/denting than what it had previously.  It seems to have worn to where it is now (ever so slight wear) and stopped.  When I close the upper and lower, the bolt carrier does push the buffer ever so slightly off the buffer retainer.  However, I am still 99% positive the tiny wear dents/marks on the buffer were caused by the retainer.  I believe that when the bolt carrier slams forward and stops in the chamber, the inertia and force allows the buffer to come forward just enough to make light contact with the retainer.  The tiny "dents" around the outside of the buffer are so small they could almost be classified as scratches, but they are infact tiny dents.  For those of you with more significant buffer marking...  unless the buffer is being stripped of a significant amount of weight OR is mushrooming to the point of possibly catching inside the buffer tube, I would not worry about it.

Anyway, this last modification and trip out has inspired much hope for me in my upper.  It's by no means 100%, but 125 rounds without a hiccup and 15 dirty ones with only 1 FTEx is promising.  I won't be completely sure until I put a couple thousand through it.

To recap the last 2 times out:

1. 62 "normal" rounds - no problem.
   8 "dirty" rounds - 1 FTEx (tapped out w/ cleaning rod), 2 FTEj

2. 125 "normal" rounds - no problem.
   15 "dirty" rounds - 1 FTEx (bolt closed over a 2nd, charging handle pulled, extracted)

I spent much of the weekend completely stripping the lower and lower and removing ALL traces of graphite from the surfaces of the various parts.  I am still flaming mad about his recommendation of graphite lube in the magazine, it got _everywhere_.  Luckily there is no corrosion, rust or darkening of metal that I can see.. must be a very slow & mild corrosion between aluminum and graphite under special conditions.

I just received some more information regarding the FAB-10.  The pistol grip area is a bit on the wide side and pushes the pistol grip outward.  My pistol grip comes in contact with the safety and puts some resistance against it.  I didn't know if this was normal or not, so didn't give it much of a second thought.  Now I know that this is NOT normal, so I will probably shave a small amount of the pistol grip to make it fit more conformatably.  Just more info for any of you considering a FAB-10.

I also received additional peel washers from CMMG, I will be re-indexing my flash hider tonight.  Thank you CMMG!

My carrier doesn't move and is flush with upper.No play when upper/lower together.Buffer looks like it moves back when upper closes on lower.

Sorry for jumping in so late. I had 3 FAB10's and the first 2 had a lot of FTE problems. One was J&T M4gery and one was CLE custom Mk12 Mod 0. I never quite figure it out until the armorer who built my Mk12 Mod 1 gave me a very good tip : "lube your bolt and carrier with CLP until is dripping with it". Ever since then I never had a single FTE on any one of my FAB10s. It doesn't seem to be the lower. I am told this is a very common problem with dry uppers.
BTW, I shoot Q3131A with the M4gery and BH 69gr SMK reman with the SPR. The FTE problem seems to appear on both but fixed with CLP on both also.

Thats odd the only oil I put on my M4 is around the gas rings  and a few drops on the bolt carrier. Thats all that I lube and i've had no FTF with my personal rifle or my Gov M4.

No such thing.



This has nothing to do with your FAB-10 lower.  I don't think a lower is even capable of creating FTEx/j's as all that action is in the upper.  CLP is not a "fix", something is not right and you should check into that.

I'm busy at work on this rifle and have a few things in the pipe and some various parts still on their way.  I should have it reassembled and ready for the range again by next friday.  Just thought I'd mention an interesting developement and ask a question.

I received the peel washers from CMMG and decided to re-index my A2 Flash hider last night.  I had to try many times to get it right.  Adding 1 peel washer put it to far, taking it away made it too short, I just had to find the right combination of varying peel washers.  I don't have a barrel vise, so I had to use the front sight tower for leverage.  I made sure to remove the gas tube first just incase anything catastrophic happened.  Despite it being a cast it held up just fine, no bent ears, nothing, perfect condition.

However, when I finished I held it up to take one last look at it and I heard a rattle.  I lightly twisted the barrel back and forth while holding the upper receiver and would hear a "click" or "rattle" each time.  I looked at the M4 feed ramps to and tried it to see if the barrel was actually moving in the upper... it was.  I am just about positive it was not doing this before.  I happened to brush the Delta ring and noticed the whole barrel nut/delta ring assembly rotated.  I easily unscrewed the barrel nut and removed the barrel from the upper.  There was no damage to where the indexing pin lined up in the upper or any other visible damage.  It appears to me the barrel nut just wasn't tight enough *shrug*.

I see an action block and a barrel wrench in my future.

Does anyone else cringe when they read that?

i emailed Fab-10 a month ago to ask a few questions about the product.The company president wanted to return the call.It looks like a nice lower.I just wish we in Kalifornia didn't have to pay $385 for a lower plus the b/s back ground check and ffl fees...Does Fab-10 attend the major Kalifornia gun shows?

haha, supposedly this is a common problem with many manufacturers.

Forgetting to tighten the Brl nut is common?

[url]http://64.177.53.248/ubb/Forum56/HTML/000497.html[/url]

Yeah, supposedly it's happened on BM's and Armalites.  I shot plenty of rounds through it, it wasn't loose or inaccurate before.  I somehow managed to work it loose while I was reindexing the flash hider.

No, but failing to tighten three times often results in barrel nuts loosening as the rifles heat up when fired.

Yikes, it's been awhile since my last post.  I've been busy and waiting for parts/tools, but I finally got my rifle put back together and took it back out to the range!  So here is the report:

Remaining issues were:

-FTF problems due to FAB-10 internal magazine.
-Excessive windage adjustment to the right.
-Flash hider needed re-indexing.
-Barrel nut came loose, upper needed to be re-assembled.

I was able to re-index the A2 flash hider as I mentioned previously, however I'm not sure that I made it clear that I did finally get it to line up almost (about 1-2mm off) perfectly centered.  Mil-spec says the top slot only has to be touching the center line of the front post, but I'm more particular in this case.

I received my armorer's upper vise block and barrel wrench from Bushmaster.  Both tools were of top notch quality and worked perfectly.  When I went to re-assemble the barrel to the upper, I shimmed the right side (if looking from the rear) of the pin with a couple peices of cut peel-washer to keep the barrel from canting to the right.  It worked great and now my windage only requires about 10 clicks to the right on my ARMS #40A2 compared to the 20 or so (leaving almost no adjustment left) required previously.  Mil-spec allows 16 clicks right.

I followed military manuals when re-assembling my upper.  I also was very careful to make sure my gas tube was lined up perfectly.  I had the problem lining up the barrel nut where one notch was only 28ft-lbs, and the next notch was over 80ft-lbs.  I did the loosen & re-tighten thing many times to make sure that I was getting good thread seal/contact between the upper and barrel nut.  However, I just wasn't getting anywhere.  So I said screw it and tightened it ft-lb by ft-lb to 84ft-lbs which provided the perfect line-up for the gas tube.  I figure that if 80ft-lbs doesn't hurt it, there has to be some kind of margin in there before damage is done and I seriously doubt that margin is only 4ft-lbs.  I also listened and "felt" very carefully as I went for any sign of damage being done.  When I was finished everything looked and seemed fine and from what I can tell, it is.  It certainly isn't going to come loose again. [:D]

The problem with the magazine, wow, where to start.  I spent about 2 hours on the phone with FAB-10's actual manufacturer and Mike the owner of ShoeLess Ventures.  Most of the time was spent explaining my problem, all I wanted to know was what size rivet is used to hold the magazine in.  I figured it out myself and Mike called me 3 days later confirming what I found out.

For background:  The Fab-10 uses a cut LEO/Military mag.  The bottom of the magazine is wide open and the lower receiver does not have a magazine slot milled out.  The receiver does have a slot cut in the bottom rear of its magazine well for the spring to be retained in.  The follower also has all the anti-tilt legs cut down to be almost flush with the remainder of the underside of the follower.  Which is just completely STUPID.  Their reasoning is that if they cut down the follower, the magazine can't be modified to hold more than 10 rounds.  It would be a felony to modify it to hold more than 10 and you'd be destroying the reliable functioning of your rifle.

More background:  My problem was that with only 2-4 rounds the rear of the rounds would be pushed down by the bolt charging rearward and stick where they are.  When the bolt came back forward it would not engage the rear of the rounds (because they're stuck too far down) and would instead smack the rounds around the neck.

Plan of attack:  I couldn't use a longer follower and still retain a 10-round capacity.  I had hoped a stronger spring would fix the problem.  It did not.  So I tried different combinations of follower lengths and spring weights (lighter, same as factory, heavier).  Nothing solved my problem.  Finally, I put a non-cutdown USGI green follower in with the normal spring, and presto, no problems.  The anti-tilt legs of the follower are ABSOLUTOLEY REQUIRED for 100% reliable function in all conditions, NO IF ANDS OR BUTS.  Unfortunately, my magazine now only has a 6-round capacity.  With that and one in the chamber I get 7 shots.  Oh well, that's as many as I get with my Mossberg 500 (7-shot tube, 8 w/ one in chamber) but without the kick and slow reloading.  What good is 10 round capacity if you don't have reliable function?  I'll stick to 6 rounds and trust my abilities to make each one count.  BTW, I also replaced the magazine body with a Bushmaster USGI Teflon-coated 10-rounder with their heavy duty floor-plate and chopped/sanded it to the same length as the cut LEO/Military magazine included in the FAB-10.  The teflon magazine is slicker, and I hoped this would help, besides I accidentally poked a hole in the original magazine removing it.

With my rifle completely re-assembled, cleaned and lubed, it was back out to the range.  I didn't have time to shoot until very late and the sun was already close to down.  I knew I would have to sight in again, so the first shots came from a benchrest.  I was worried about my accuracy because of how tight I put the flash hider on, and how tight I had to mate the upper to the barrel.  From 50 yards w/ irons I was able to print 2 3-shot groups where 2 of the rounds were touching each other and 1 flier was about 1-1 1/2" away with Q3131A.  I don't believe the rifle's accuracy degraded at all, I think it was just me trying to be quick about it and the low light making things difficult.  I'll have to try again during day time.

I plan on trying as many ammunition types as possible with this firearm to make sure it is reliable.  I don't want to be operating on the edge of reliability.  I put 80 rounds through it that night (takes awhile with a 6-round magazine).  This time I used 20 rounds each of Q3131A, XM193, Wolf 55gr and PMC 55gr.  Each ran flawlessly.  I also did a 7-round FA (bump fire.. as close as I can get to FA)  dump of XM193 to help establish where this rifle stands on reliability after all my work on it.  It ate it right up without a problem.

Since it was dark out I also checked the flash.  XM193 spit out a softball sized flame, Q3131A the same.  Not bad.  Wolf had very little flame basically coming out of the A2 Flash hider ports.

I collected as many casings as I could see, but it was difficult because I was on the move a lot, doing drills and it was dark out.  However, I did manage to get probably 70 of them.  Came rim extractor markings were all light to moderate.  The wolf showed no marking at all.  PMC had pretty moderate marking, looks like they use somewhat softer casings.  XM193 and Q3131A both had light to moderate markings.  I have not had an extraction problem in 267 rounds (not counting the filthy rounds I put in dirt) since polishing the chamber.  I'm going to be putting boxes Remington UMC, S&B 62gr, and other ammunition through it in short order to further establish reliability.  Oh, and WOLF STINKS AND IS FILTHY! ICK, I will not be using it in the future for anything but to help establish how reliable a rifle is.

That's all for today, it appears my problems are solved.  I have nothing in the pipe that needs fixing on this rifle anymore.  I've also figured out a way to legally get my 10 round magazine capacity back without sacraficing reliability but that's a few months off AT LEAST.  My rifle appears to be complete!

wyv3rn, that's a good write-up, thanks for the info. That's exactly the kind of info I was looking for regarding CA legal lowers.

Was your lower stripped or complete, for the price you paid?

wyv3rn,

Great job, it looks like you're finally smoothing out this carbine!  I'm glad it's working better for you.

BTW, you should be okay with the barrel nut at 84 ft.lbs.  IIRC, the torque range for the barrel nut is about 80 to 125 ft/lbs.

Cheers![:D]

Thank you.


Stripped, $269+tax+DROS came out to $310.  I paid for a standard Bushmaster small parts kit and ended up getting the pick of the litter IMO.

Thank you!  The military manual said at least 30ft-lbs, and don't go over 80ft-lbs.  Where does the 80ft-lbs to 125ft-lbs figure come from?  I'm not trying to knock you down or anything, but it would put my mind even further at ease if I could read this from a military or manufacturer source.

I believe the source is Colt.  I remember a long thread about this on the Building forum and a several people mentioned this.  You might want to ask Tweak to confirm these numbers but they should pretty close if not right on.

Glad you got it fixed!
What part of CA are you from? If you're in the Bay Area, what range lets you rapid fire?
I wouldn't mind bumping 76 rds out of my AK or 31rds off my AR. [:D]

Also, I'm thinking of getting a FAB-10 as well. But, I'm going to turn it into an SPR type rifle. Already have me an M4 type.

It's a range on privately owned land, but the land is not mine.  The owner didn't like me bump firing but didn't mind since it was only 1 string of 7 rounds and it was for a good cause. [:D]

Edited:  I should say, "allowed it" not "didn't mind".  He still wasn't exactly fond of it.

Took the rifle out again for some more fun and testing.  This time there was some light at the beginning of my shoot.  Doesn't look like accuracy was hurt, I was able to make a couple .8-1.0" groups @ 50y (iron sights, S&B M193 & XM193) without a problem.  I didn't clean my rifle since the last time it was out.  I could still smell that Wolf ammo.. gag me.

Anyway, I wanted to test with 3 new types of ammo.  I brought with me another 80 rounds, 20ea of Federal American Eagle 55gr, S&B M193, Remington UMC 55gr and Federal XM193.  No hiccups, case rim markings were light with a couple moderates.  I haven't really seen case rims after being fired through other ar15s.  So my definitions of light, moderate and heavy are basically:

Light:  An extractor mark, maybe SLIGHT deformation of the rim.

Moderate:  Deformation of the rim UP TO about half of it's width, where the extractor made contact.

Heavy:  Rim nearly demolished where extractor ripped corner off or worse.  Nearly an FTEx or infact an FTEx.

Where would you say your rifle falls as far as case rim wear and do you have a carbine (16" or less) or a rifle (18" or more)?

So that's 347 rounds since my last failure, and the rifle is eating everything I throw at it.  Maybe I should try some Olympic. [BD]

On a side note, I took my Glock 22 out to try some Win RA40T through it for the first time.  Wow.  I was shooting @ a simulated 300y@50y silloet target from 9 yards to simulate the target at 50-60 yards.  All I got was one big ragged 1+1/2" hole in the torso area.  I've always felt my G22's accuracy was sub-par compared to other reviews I had read, I think I found the ammunition it likes.  Also got a chance to shoot it in extremely low light.  The flash was baseball sized and very dim+dull orange.  When looking down the sights and shooting, you didn't hardly see it and it certainly didn't hurt my night vision.

Can anyone here double-tap into a life-size sillohet's CoM or head @ 50y with a 40S&W (full-power load, not Wolf, etc.) or heavier recoil pistol?  I'm thinking of stepping down to 9mm because I can only put a quick double tap into the CoM @ 30y or less.  Maybe I just need more practice or stronger muscles to control the recoil?

TIA

No I still haven't cleaned my rifle...

Ok, so even though my rifle has been functioning ok, I did not like the case rim deformation that was occuring.  Most of it was (what I considered to be at the time) light, but there were some moderates in there.  Also, the extraction mark revealed that there was a fair amount of extractor lift as the extractor mark was further out on the edge than I would've liked.  I inspected some casings from a friend's Mini-14 and all his case rims had were marks and maybe the TINSIEST bit of deformation on a case rim here or there.  I hadn't had an FTEx in 300+ rounds, but I still felt that I was operating on the edge of reliability.

The case rim marks, the seemingly hard recoil snap (for such a small round) and other things led me to believe maybe I was getting to much gas.  The action was unlocking and cycling before the chamber pressures had subsided enough to allow the casing to release its pressure against the chamber walls.  So I decided to try to slow down the action.

I also discovered that my firing pin retaining pin was quite bent, at first I thought it was a normal amount of bending but after more and more reading, I was considering the possibility that my notched hammer was catching on the firing pin was likely.

So I did two things.  I purchased a heavy "H" buffer along with SAW's extractor spring setup from SAWLESALES.com.  I also purchased a surplus M16 bolt carrier group from CDNN Investments.

I dremmeled back the sear trip area of the M16 bolt carrier 1/4".  When I was finished I smoothed and polished the dremmeled areas to leave no jaggies behind.  This still left more metal in this area than my other bolt carrier.  Also, it had a fully protected firing pin which should alleviate the firing pin retaining pin bending and possibly creating an incredibily dangerous situation.  There was a noticeable difference in weight between this bolt carrier group and my original - the new one was much heavier.  The very weak extractor spring included in the bolt was replaced with the SAW spring & insert.  Headspace checked out fine.

At the range I started off with my original bolt carrier group with just the "H" buffer replacing the standard carbine buffer.  Case rim deformation was somewhat lighter than before - an improvement.  I then changed out the bolt carrier group with the surplus M16 bolt carrier group.  WOW.  The difference was night and day.  Case rims had nothing but a surface mark on them, a few were SLIGHTLY (and I mean almost not even worth mentioning type slightly) deformed, definetly more along the lines of what has been described to me (and inspected by me from other rifles) as normal.  My definition of case rim deformation has been redefined and what I used to consider light I'd now consider moderate or heavy.  There just isn't anything but a surface mark anymore, it's beautiful.  On top of that, the mark showed no signs of extractor lift as the mark went deep into the case rim groove.

Recoil felt lessened and much softer.  The rifle no longer pulled to the right with a solid snap.  After being used to recoil that wasn't too far off from 7.62x39mm, this seemed like a 22LR.  I wasn't the only one who commented on how much softer the recoil seemed and "they" didn't know I had replaced anything.  They just said it felt lighter than before.  Measurable improvements in my accuracy could also be recorded.  This rifle REALLY shoots like a dream now.

I also did some bump firing to help ensure reliability.. no problems.

I am incredibly happy with these changes in my rifle and for the first time I feel that it is operating exactly as it should and with a high margin of reliability.

On a side note, the fit between the upper and lower has loosened up some, there is no wobble, but it's now very easy to pull that take down pin.  Reloading takes about as much time as reloading an SKS with a stripper clip.  I know what you're thinking.. that blows.  It's better than before though.. I used to need a punch and a hammer to drive the take down pin out to reload. [BD]

Is it legal to have a pre-ban upper (ie flash supressor & bayonet lug) on the CA legal postban lower?

Yes, you can have all the pre-ban features you want.  It is a fixed 10-round magazine and thus the rifle is treated like any bolt-action.  I thought this was covered earlier in this thread?