AR15.Com Archives
 Cant get my M16 to run
opengun  [Member]
6/10/2011 11:39:58 AM EST
I have been to the range 5 times now trying different combinations to get my PAWS M16 to run. When I recieved the gun it was just a NIB reciever and I assembled it with all new mil spec parts. The issue seems to be bolt bounce for when the gun stops the hammer is on the firing pin with a light hit. The most rounds its been able to dump was 10-15 with the H2 in it. I have tried Carbine, H, H2, and H3 in the collapsable stock as well as puting in a wolf XP spring. I also tried the rifle stock and still the same problem. This is with 4 different uppers 10.5, 11.5, and 16in configs. I have checked the timing per the DIAS method and it drops with the .10 pin. Ammo has been Wolf, Seller & Bellot, and LC M855. Gun seems to run best with the H2 or rifle stock. Is there anything else i should try? This is getting to be an expensive paper weight

P.S. anyone in the San Antonio area with a working gun that would be willing to swap uppers, etc to help find the problem. My friend as a LL link so cant swap with him.
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Shermantor-AR15  [Member]
6/10/2011 2:05:12 PM EST
Who's Mil-spec parts did you use? Bushmaster, DPMS, Colt, etc..???

You said it tends to run best with H2 buffer or rifle stock not sure what you mean but are you having any of the same problems with the rifle stock? can only get it to run about 15 rounds before a light primer strike with the rifle stock on it?

Are you using the same complete bolt on all the uppers? or does each upper have it's own bolt?

Have you tried to see if you could shoot a full mag or 30 rounds on semi?

Which kind of mags are you using?

I'm just wanting to know more, but others might be able to diagnois it better for you.
gmtmaster  [Member]
6/10/2011 2:24:29 PM EST
Take the thing back to A1 bone stock rifle config. Do not hang crap on the gun, mess with buffers. etc. Start from dead stone cold stock and see what it does.
opengun  [Member]
6/10/2011 2:35:21 PM EST
Originally Posted By Shermantor-AR15:
Who's Mil-spec parts did you use? Bushmaster, DPMS, Colt, etc..??? bushmaster

You said it tends to run best with H2 buffer or rifle stock not sure what you mean but are you having any of the same problems with the rifle stock? can only get it to run about 15 rounds before a light primer strike with the rifle stock on it? Same problem with rifle stock light primer strikes

Are you using the same complete bolt on all the uppers? or does each upper have it's own bolt? seperate bolts

Have you tried to see if you could shoot a full mag or 30 rounds on semi? only shot about 5-10 rounds in semi and it worked fine

Which kind of mags are you using? pmags

I'm just wanting to know more, but others might be able to diagnois it better for you.


answers in red
opengun  [Member]
6/10/2011 2:36:10 PM EST
Originally Posted By gmtmaster:
Take the thing back to A1 bone stock rifle config. Do not hang crap on the gun, mess with buffers. etc. Start from dead stone cold stock and see what it does.


Did this with the 16in upper

hawkin  [Team Member]
6/10/2011 3:45:11 PM EST
Edited.. Thinking of to many things at once.
Shermantor-AR15  [Member]
6/10/2011 3:50:01 PM EST
Originally Posted By hawkin:
Check your gas tube for a crack and ensure it's not missing the roll pin. I also had an upper with an out of spec bolt release that caused mine to not function correctly.

as he stated problem is with 3 different uppers, so that would be 3 4 different gas tubes or 3 4 different carrier keys. Also the bolt release is always in the Lower when it comes to .223/5.56 uppers. Are you tired?

223monkey  [Member]
6/10/2011 3:51:57 PM EST
Originally Posted By opengun:
I have been to the range 5 times now trying different combinations to get my PAWS M16 to run. When I recieved the gun it was just a NIB reciever and I assembled it with all new mil spec parts. The issue seems to be bolt bounce for when the gun stops the hammer is on the firing pin with a light hit. The most rounds its been able to dump was 10-15 with the H2 in it. I have tried Carbine, H, H2, and H3 in the collapsable stock as well as puting in a wolf XP spring. I also tried the rifle stock and still the same problem. This is with 4 different uppers 10.5, 11.5, and 16in configs. I have checked the timing per the DIAS method and it drops with the .10 pin. Ammo has been Wolf, Seller & Bellot, and LC M855. Gun seems to run best with the H2 or rifle stock. Is there anything else i should try? This is getting to be an expensive paper weight

P.S. anyone in the San Antonio area with a working gun that would be willing to swap uppers, etc to help find the problem. My friend as a LL link so cant swap with him.


don't think it is your upper, considering you have already tried 4 different uppers and are able to replicate the problem. Can you post up some pics of the inside of the lower, that would go a long way towards trouble shooting.
chopps  [Member]
6/10/2011 3:56:30 PM EST
Originally Posted By gmtmaster:
Take the thing back to A1 bone stock rifle config. Do not hang crap on the gun, mess with buffers. etc. Start from dead stone cold stock and see what it does.


What he said above is best.
Establish a baseline then go from there.
KarlSG1  [Team Member]
6/10/2011 4:15:08 PM EST
You mentioned checking timing with a 0.10 pin. What diameter pin does it NOT drop the hammer with? Extra stout recoil springs can make bolt carrier bounce issues worse. Assuming you have the hammer spring legs installed correctly, and you are having hammer down stoppages with a rifle buffer, spring, and receiver extension, then, IMHO, your hammer is being released too early, or it is not being caught by the autosear at all during the dynamic firing cycle. Are the final engagement surfaces of your autosear, and/or the autosear hook on your hammer rounded off? Does the autosear pivot freely, or does it bind? Does the autosear have good engagement with the hammer hook? (A pic. might help here.) Does the slot in the safety/selector that interfaces with the autosear bind it or excessively limit it's travel?

Karl
astrafire  [Member]
6/10/2011 5:04:29 PM EST
I think the bolt may be dragging on the pmag.
You can check by inserting an empty pmag, and then manually pulling the bolt back slowly while feeling for any vibration in the fully seated pmag and also letting the bolt slowly go forward while feeling the pmag. You are specifically checking for any vibration or noise indicating rubbing of the lips of the pmag on the bottom of the bolt. If there is a rub, switch to GI-type mags or Lancers.
gmtmaster  [Member]
6/10/2011 5:46:05 PM EST
Is this gun a remanufactured Oly/ PAWS... A2 configuration?
opengun  [Member]
6/10/2011 6:09:44 PM EST
pictures

URL=http://imageshack.us/photo/my-images/199/061011038.jpg/][/URL]

opengun  [Member]
6/10/2011 6:14:06 PM EST
rechecked timing and the smallest pin that will not release hammer is .111, .110 will release with presure on the forward assist. Autosear seams to pivot freely with no binds.
opengun  [Member]
6/10/2011 6:15:23 PM EST
Originally Posted By gmtmaster:
Is this gun a remanufactured Oly/ PAWS... A2 configuration?


not one of the replacement recievers so should be A1 config
tony_k  [Moderator]
6/11/2011 5:23:01 AM EST
From the pix, one thing to check is if the autosear pin hole was drilled absolutely perpendicular to the receiver wall. Inthe horizontal pic, it appears that the autosear is slightly canted to the rear, compared to the takedown pin. This is not uncommon for RR conversions –– the drill started out in the right location but the bit cut at a slight angle, so by the time it reached the far receiver wall, it was out of position.

An autosear with a slight angle to it can pass the "static" release test and still move freely by hand, but the geometry is off just enough that when running at 12 cycles per second (750 rpm), it fails to function correctly.

If that is not the culprit ... I will second the above vote to go back to Gene Stoner's original design.

Get Colt fire-control parts and all brand-new springs. They are a known military contractor/supplier, and you know that their parts are not just attempting to reach the milspec, they have passed .gov quality control.

Install a USGI rifle receiver extension (buffer tube), with a correct milspec rifle-length buffer and a new rifle-length recoil spring. Make absolutely certain that it also is straight and alinged with the receiver.

Borrow a low-mileage Colt 20" milspec FA upper, preferably an M16 or M16A1. Use a new Colt BCG, or else make sure the bolt carrier is properly staked, the gas rings as-new and correctly aligned, etc.

Use only as-new USGI contract mags that have been test-fired in another gun for function.

In other words, build a complete, as-new GI-issue 1960s era Colt M16/A1 around your receiver, as originally designed by Gene Stoner and manufactured by Colt to Armalite's plans. That way, you eliminate all the variables.

If it still does not run, send your receiver off to M60Joe, because there is something seriously wrong with it.

If it does run, start swapping in one of your components at a time, until you have tested them all.

And keep the Colt FCG parts and new springs. Trust me, you need them.

HTH.
Burnsome-  [Team Member]
6/11/2011 6:29:44 AM EST
ditto's on the above +......

not sure if mentioned yet, but most 16's i've worked on (that were running too fast - and if that's the problem) were able to be fixed by swapping out buffers with an endine or an AAC rate reducing buffer.
gmtmaster  [Member]
6/11/2011 6:45:27 AM EST
Originally Posted By Burnsome-:
ditto's on the above +......

not sure if mentioned yet, but most 16's i've worked on (that were running too fast - and if that's the problem) were able to be fixed by swapping out buffers with an endine or an AAC rate reducing buffer.


That is not the problem. OP's gun does not run.
Burnsome-  [Team Member]
6/11/2011 8:04:15 AM EST
from OP

The issue seems to be bolt bounce for when the gun stops the hammer is on the firing pin with a light hit. The most rounds its been able to dump was 10-15 with the H2 in it.


That is not the problem. OP's gun does not run.


ok. i thought the problem was that it does run, but only runs a few rounds and then stops?

sounds like it could be a cycle rate problem to me (running too fast). i've seen a lot of 16's that experience those characteristics generally being a timing problem, and in many cases, slowing down the cycle rate tends to fix them, and using a rate reducing buffer does that....

might be worth a try...just sayin'....YMMV...
opengun  [Member]
6/11/2011 9:37:11 AM EST
Where can I get Colt fire control groups, I can only find bushmaster.
tony_k  [Moderator]
6/11/2011 9:52:22 AM EST
Originally Posted By opengun:
Where can I get Colt fire control groups, I can only find bushmaster.

Brownells, or Specialized Armament Warehouse (http://www.specializedarmament.com), or Dennis Todd (DToddmgREMOVETHISSPAMGARD@AOL.com) ... authorized Colt LE dealers and distributors often either stock them or can order them for you.
KarlSG1  [Team Member]
6/11/2011 9:55:12 AM EST
I should have been a little clearer. I meant to suggest a pic. showing how much engagement the autosear has with the hammer. It would help if your camera is in a macro setting. Your timing check of releasing at 0.110" is right in between Quarterbore's listed ideal 0.100" and too early 0.120". I prefer timing to be a little later. Maybe swap the hammer and/or the autosear and see if you can get your timing set a little later? It is also possible for it to pass the timing check, and still fail to work during live fire.
opengun  [Member]
6/11/2011 3:50:42 PM EST
Originally Posted By KarlSG1:
I should have been a little clearer. I meant to suggest a pic. showing how much engagement the autosear has with the hammer. It would help if your camera is in a macro setting. Your timing check of releasing at 0.110" is right in between Quarterbore's listed ideal 0.100" and too early 0.120". I prefer timing to be a little later. Maybe swap the hammer and/or the autosear and see if you can get your timing set a little later? It is also possible for it to pass the timing check, and still fail to work during live fire.










here are pictures of sear engagement and hammer tip
opengun  [Member]
6/11/2011 3:54:45 PM EST
Ok, I think i found the problem. I don't think I have enough engagement between the autosear and the hammer. i can pull the hammer off the sear with my thumb. I'm sure you shouldn't be able to do that.
Shermantor-AR15  [Member]
6/11/2011 4:12:56 PM EST
Originally Posted By opengun:
Ok, I think i found the problem. I don't think I have enough engagement between the autosear and the hammer. i can pull the hammer off the sear with my thumb. I'm sure you shouldn't be able to do that.


I was going to say that hammer tail for the sear doesn't look "MIL-SPEC" to me.

You can find everything Colt "MIL-SPEC" M16 FCG at brownells. Some of the stuff might be on back order
http://www.brownells.com/.aspx/cid=0/k=full+auto/t=P/avs%7cManufacturer_1=COLT/Products/All/COLT/search=full_auto
tony_k  [Moderator]
6/11/2011 5:26:46 PM EST
Yup. That's the problem with non-Colt "milspec" parts. Here's what the Colt, true milspec looks like:



You can see how you can have functional issues. Sigh.

Also BTW, if the hammer is that far off ... who knows what dimensions are off on the trigger, disconnector and selector.

Bite the bullet, buy Colt. And start shootin'.

BTW, if you have a C&R FFL you can get dealer pricing for parts from Brownell's, which cuts the price for the "A1" hammer from the $55 retail to $44 ... and if you watch the boards (in particular subguns and sturm) and know what true milspec parts look like, you can often find a complete NIB Colt set for well under $200, sometimes as little as $100.

Good luck!



opengun  [Member]
6/12/2011 8:12:29 AM EST
I ordered a Colt complete lower kit from Specialized Armament Warehouse. Will keep you all updated when the kit comes in. thanks.
jbntex  [Member]
6/13/2011 8:09:35 PM EST
Is the auto sear new? Its hard to tell from the pictures but it looks like the autosear that came with my Oly and which had the top of the pivot pin arms ground down as somebody once wanted to use an upper that didnt have the proper sear relief cut and instead ground down the sear. If this was the case somebody may have originally used this lower with an upper without the proper relief cuts and the auto-sear may be tweaked as a result, causing improper hammer contact or timing issue. If the sear isnt engaging the hammer ear properly that the hammer could be getting released upon recoil when the bolt hits the buffer tube bottom, and recoil vibrates the hammer off the sear and it just ends up riding the carrier home. Which may explain a couple shots and then a light primer strike.

If you have not replaced the auto sear, I would definatley consider replacing it with a mil-spec new one.

If you replace the fire control components and all else fails and you still cant get it to run I am willing to help you. I am not in SA, but am in Austin (approximatley 1.5 hours from the 281/410 / SA Airport interchange - I used to make the drive to SA every week for work). I have helped a few local members with their SBRs and M16s and have yet to get one to run properly so if you wanted to make the trek up to Austin I could most likely get it fixed up for you.

I also have an Oly /SGW lower that runs like a sewing machine as well as multiple buffers, uppers, springs, etc. that we could use to debug until we figure out the combination that works for you.

I hate to see somebody give up on a perfectly good M16.

James
tony_k  [Moderator]
6/14/2011 3:44:17 AM EST
James, over the years I've dealt with several Oly conversions that had a too-high top deck –– the top edge of the lower receiver where it meets the upper receiver –– as well as incorrectly located rear takedown pin holes. In some cases, you could modify the parts involved rather than touch the receiver itself ... but it often caused functional issues down the road.

You are correct about replacing the autosear –– I consider that part of the fire-control group, and when replacing the FCG, the sear needs to be done as well. Sorry I didn't point that out.
jbntex  [Member]
6/14/2011 10:58:08 AM EST
Tony you are correct about the auto-sear being part of the FCG. However, it's been my experience that most vendors seem to pull the autosear from most M16 FCG "packages" and make you order it separately. Probabably because of some stigma that it is the "evil/controlled" part of something like that.

The pictures look like somebody may have already worked on the top edge of the receiver as the annodizing doesnt look like it is still there.The top receiver ledge/edge is purplish and seems differ from the rest of the annodizing and that looksa bit "streaky like somebody touched up the exposed metal with a black sharpie marker

As with some Olys there may be some factory dimentional variation of the ledge height, rear takedown hole, or both, homebuilder F1 issues with the autosear hole, and well as a mix of low quality or modded parts that all needs to be sorted out. My Oly just needed the rear lug on the first upper I bought filed out just a touch. After the first couple rounds or som the high spots on my receive seem to have naturally worn down and all uppers from there on out have fit just fine.

Without seeing the gun, my best guess is a problem with the hammer to auto sear engagement since the way they are locking up in the pics doesnt look just right.. The hammer may not be held back properly during active firing where the recoil energy is much greater vs. dry cycling the gun. That just a guess though without seeing it in person.
jestertoo  [Team Member]
6/14/2011 3:48:37 PM EST
deleted
mike12345  [Member]
6/23/2011 6:20:26 AM EST
Originally Posted By opengun:
here are pictures of sear engagement and hammer tip


Where did you buy this "bushmaster" trigger group? Thats not a bushmaster hammer, bushmaster hammers have an F2 stamped on the side. I've used plenty of bushy ful auto trigger groups ordered direct from the factory and didn't have a problem with any of them. I even used one in afghanistan.


ETA pic of bushmaster. Note F2 on hammer and F4 on trigger. I doubt bushmaster makes these, they probably buy them from a mil contractor, probably the same place that makes colts.



heres a pic of my colt enhanced, much better

KarlSG1  [Team Member]
6/24/2011 5:32:29 PM EST
Update?
opengun  [Member]
6/25/2011 7:45:47 AM EST
Went to the range yesterday with new Colt FCG installed and gun runs great with H2 buffer with all ammo except Wolf. Only way I can get wolf to run is with my suppressor installed. thanks for all the help.
Dragracer_Art  [Team Member]
7/2/2011 7:52:43 AM EST
Originally Posted By opengun:
Went to the range yesterday with new Colt FCG installed and gun runs great with H2 buffer with all ammo except Wolf. Only way I can get wolf to run is with my suppressor installed. thanks for all the help.


Sounds like the gas port could stand to be opened up a tad, or maybe a little lighter weight buffer. Obviously the cyclic rate will go up a little too.

I think since you are back to a working Milspec FCG, you can probably get away with a stock weight buffer and OEM spring. That may cure the problem with Wolf ammo.
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