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Posted: 1/2/2006 9:53:52 AM EDT
[Last Edit: 2/15/2006 3:39:53 PM EDT by Hyperformer]
Some history...In the past had double feeding problems and deburred extractor and installed o-ring....no double feeding since. 16" m4 BUSHY


Lately installed a VLTOR modstock and used my original buffer & spring instead of the new one that came with the stock.

Shot numerous mags of fed & win white box & some 5.56 without a hickup. Thought I would try Wolf 55gr for the 1st time(polymer coated). From the get go I had failure to feed after 1 shot. I then tried the SSTest with 1 round in the mag and the bolt catch consistently caught the carrier and NOT the bolt face.

Upon inspecting the rifle, I was comparing my original buffer to the new one and discovered the roll pin on my orig. bushy buffer stuck out about an 1/8 inch. Could this have been the cause of my SS from potential drag on the buffer spring?

My carrier and key are solid. There is normal wear on the gas tube mushroom, everything was cleaned and lubed with CLP. I noticed some carbon marks(buildup) on the gas tube behind the FSB....how much is normal?

I have yet to shoot again with WOLF, but do you think I shouldbe concerned? Ohhhh.....I replaced the orig. spring & buffer with the one VLTOR sent.
Link Posted: 1/2/2006 11:25:11 AM EDT

Originally Posted By Hyperformer:
I then tried the SSTest with 1 round in the mag and the bolt catch consistently caught the carrier and NOT the bolt face.



It's definitely short stroking then. Have you tried it since you swapped in the new buffer and spring? Wolf is underpowered anyway, and if your rifle is a borderline "short-stroker", this will cause the symptoms to show up.
Link Posted: 1/2/2006 12:49:43 PM EDT
No, I haven't tried it yet. Also, does it matter much lube the stock tube gets? I lightly oiled the spring & buffer...that's it.
Link Posted: 1/2/2006 12:53:29 PM EDT
I guess my one concern is gas leakage from the FSB. The carbon marks are on the gas tube about 1" back from the FSB. Is that normal?
Link Posted: 1/2/2006 1:17:27 PM EDT
I never lube my buffer spring at all. As for the carbon build-up on the gas tube, you'll get a little leakage there since the gas tube/FSB mating surfaces aren't press fit.
Link Posted: 1/2/2006 2:03:35 PM EDT
Wolf can be problems on a newish/tight chamber. You might have to break the rifle in a bit more until the ammo will run with the chamber, or you can try to just the upper bearing surfaces a tad more wet with CLP to see if it helps.

Also, if you haven't done so, now is a good time to check the key to make sure it's still tight on the carrier.
Link Posted: 1/2/2006 2:05:44 PM EDT
Link Posted: 1/2/2006 3:04:28 PM EDT

Originally Posted By Tweak:

could be

does the bolt lock open properly manually?



I assume you mean with an empty mag and manually charging rifle......yes....perfectly.
Link Posted: 1/9/2006 9:22:55 AM EDT
[Last Edit: 1/9/2006 12:44:47 PM EDT by Hyperformer]
I got out this weekend and was able to do some shooting. I picked up some 62grain Wolf and still had the 55 grain. Started out with the 55gr. which was what I was shooting when I first noticed the problems.

Loaded 1 round and the the bolt catch caught the bolt face. Hmmm good.

Loaded a mag and did some blasting and at the end of the mag, the bolt catch grabbed the carrier again....hmmmmm...not so good.

Did some more shooting with the Wolf, and had 1 fail to feed.

I broke the rifle down that night and decided to check my gas tube by pulling it out for the 1st time. (a lot easier than I thought) I checked the "acorn" which I thought was in great shape from my visual inspection which basically consisted of looking down inside the receiver at the gas tube. The first thing I noticed was the unusual amount of wear on the top side of the tube. The flared "acorn" was worn flush or even with the rest of the tube.

Do I need a new gas tube? There doesn't appear to be any binding, and when I mate up the tube and gas key outside the rifle, there seems to be a good fit. I have a strong feeling this could be causing my problem. THOUGHTS????
Link Posted: 1/10/2006 4:42:16 AM EDT
anyone????
Link Posted: 1/10/2006 7:04:54 AM EDT
[Last Edit: 1/15/2006 5:42:07 PM EDT by Dano523]
.
Link Posted: 1/10/2006 10:28:52 AM EDT
[Last Edit: 1/10/2006 10:58:30 AM EDT by Hyperformer]
Called Bushmaster this morning. They said my wear on the gas tube wasn't all that irregular and shouldn't be causing my problem. They suggested I do a blow test on the BC and bolt- checking for a gas leak around the gas key. This involved sticking a tight fitting straw on the end of the gas key, and while holding the bolt in it's rearward position, checking for bubbling around the base of the gas key. Zero leakage at the gas key, but it seems I get leaking around the bolt inside the carrier. Seems my gas rings may be bad??!!?

By the way...brass ammo like Q3131 and UMC run just fine in this rifle. Cases eject at the 4:00 position about 8'.
Link Posted: 1/10/2006 11:31:52 AM EDT

Originally Posted By Hyperformer:
Seems my gas rings may be bad??!!?



Yeah, it's possible. I put together an upper a while back with all new parts, including a new BCG. I had short stroking problems from the start. There were no obvious problems, so I changed the gas rings just to be safe. Sure enough, that cured the problem. The original rings were new, and I could not see any thing wrong with them. But apparently there was. They are only about $3, so go ahead and give it a try.

Good luck.
Link Posted: 1/10/2006 3:31:11 PM EDT
Where is the best place to get gas rings and a gas tube from? I know this should be a warranty item, but Bushmaster seems really against just sending out parts, and I want to avoid sending my upper back to them. For the money it would cost to send it back to them, I might as well get the parts & try it myself....perhaps learn something in the process.
Link Posted: 1/10/2006 5:31:35 PM EDT
I have had the same problem with my Bushmaster and recieved an e-mail from them telling me to do the blow test. I also removed the gas key and cleaned the crap out of everything. I found no gas leak per the blow test. I have been using department issue Federal TRU ammo, which is supposed to be the bee's knees.

I also have an ACE skeletonized stock on the thing. I read about a problem with the buffer hitting the butt-stock screw so I took the rubber but pad off to remove the screw and see. Under the buttstock I found....a screw not screwed into anything. It fit the top screw hole when I removed the uber-long screw. SO....this screw was just sitting there with no apparent function. What the...

I have not had a chance to shoot the thing yet but I will report back.

Thorfin
Link Posted: 1/11/2006 9:17:09 AM EDT

Originally Posted By Hyperformer:
Where is the best place to get gas rings and a gas tube from?



You can order them off of the Bushmaster web site, or just about any of the vendors in the EE. You can also get them from Fulton Armory.
Link Posted: 1/11/2006 2:57:24 PM EDT

I also removed the gas key and cleaned the crap out of everything. I found no gas leak per the blow test.

If you disassembled the gas key, be sure to re-stake it, preferably using new screws.
Link Posted: 1/14/2006 7:30:23 PM EDT
I did restake the screws and as Bushmaster recommended I put a dab of LOCKTITE on the threads. Shot the thing but it still had the same feeding problems. The round is not chambering and appears to be getting bound up on the bottom two locking lugs. It is putting huge gashes in the round. I have also noticed when cycling the action by hand I can create a problem where the hammer locks the bolt half-way open on the firing pin.

I don't know what to do about this.

Thorfin
Link Posted: 1/15/2006 7:34:07 AM EDT
[Last Edit: 1/15/2006 7:35:12 AM EDT by wrecktech]
You mentioned in you first post that you used the original spring and buffer, not the one that came with the stock. Have you checked if there is any difference in length between the original spring and the VLTOR spring? Are the buffers the same weight?

I am thinking that you might have a too long spring stuffed in a shorter space and that is interfereing with the firing cycle.
Link Posted: 1/15/2006 9:36:42 AM EDT
[Last Edit: 1/15/2006 9:43:40 AM EDT by Triple_D]

Originally Posted By Thorfin:
....I can create a problem where the hammer locks the bolt half-way open on the firing pin.



Ah...you have a non-shrouded bolt carrier. Does the outside edge of your firing pin collar look like the one in this thread? Having the hammer bleed too much energy off of the bolt, by catching on the firing pin, can definitely contribute to/cause short stroking.


EDIT: Sorry to get sidetracked on your thread Hyperformer, but since y'all are having similar problems....
Link Posted: 1/15/2006 2:21:20 PM EDT
[Last Edit: 1/15/2006 2:43:30 PM EDT by theshootersden]

Originally Posted By Thorfin:
I have also noticed when cycling the action by hand I can create a problem where the hammer locks the bolt half-way open on the firing pin.

Thorfin



The AR15 carrier doesn't have a shroud to hide the head of the firing pin... The AR15 hammer has a section removed at the top front side of it... What your experiencing is perfectly normal and is caused by the hammer (the area that is cut out) getting caught on the head of the firing pin... This is done intentionally to prevent full auto fire when the disconnect is removed or broken...

The M16's carrier has a full ramp or "shroud" protecting the firing pin, a firing pin with a larger head, and a hammer that isn't cut... It will not catch and lock like the AR's do...
Link Posted: 1/16/2006 9:32:33 AM EDT
The VLTOR spring was about 3/4 of an inch longer, and both buffers appeared to be standard.

I too thought that perhaps the new stock was a touch shorter, but manually charging the rifle feels the same as before, with no binding issues whatsoever.

I pulled the gas tube and cleaned that very well and also cleaned up the tip of what looked like burs on the inside edge. I have yet to order the new gas rings....looking at the McFarland 1 piece as my blow test seemed to indicate some sort of leakage, and the rings don't look so hot. (tip of on is bent a little, and the rings seems to be of varying diameter.

I will post results after the new parts come in.
Link Posted: 1/23/2006 3:20:46 PM EDT
Ok, got out this weekend after replacing gas rings and a thorough check of the gas system.

Gun runs flawless on brass .223 WWB from wally world.....as it always has.

Still short stroking the WOLF, but not nearly as regularily. I assume this will creep up more as rifle gets dirtier.

My question is....the only thing I can think is causing the SS is a slightly "off center" front sight...ie the barrel gas hole is not properly indexed to the front sight base gas hole...thereby restricting gas. My reasoning is this....the base appears to be canted slightly left in relation to the rails on my upper receiver. The rear sight alignment however is dead center.

Thoughts? Also, if I put aftermarket parts on my bushy, does that void the warranty?
Link Posted: 1/30/2006 2:52:19 PM EDT
Yes...Yes and I think you are on to something. The firing pin collar is beat to hell. I have contacted bushmaster and they are going to fix it. I fiddled around with it a little more and I can actually get the bolt to hang up by not allowing the trigger to reset when charging and empty weapon.
Thanks

Thorfin
Link Posted: 2/15/2006 3:39:27 PM EDT
OK. Everything seems to be running good now. I replaced the suspect gas rings and cleaned the inside of the FSB along with a thorough cleaning of the gas tube.

Runs with WOLF....I am happy.
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