Had a disappointing day on the range last weekend.  Mutt gun ran like a top with multiple  types ammo:  Wolf  55gr, PMC 55 gr, and SS109.  Bushmaster wouldn't run for crap.  Doesn't like the Wolf ammo, only shot PMC and SS109.  Here's the problem:

It would fire one round, cycle the empty, reset hammer and "CLICK", would not pick up next round from magazine.

Used brand new USGI, green follower magazines, proofed in the other gun that DID run that day.

No weird wear marks, nothing out of place, etc,etc.  I did notice a slight hesitation when hand cycling the bolt, about halfway through it's travel.  Went home a switched the crappy/cheap four pos stock for a RRA six pos M4 stock and haven't had the chance to get back out to shoot yet.

Any suggestions?

This sounds like short stroking to me.  What buffer are you running?  H, H2?  Wolf may not have had enough power to cycle reliably in your rifle.  MJD

Check to see if your gas key is leaking at the carrier.
Spray some light oil around the gas key/carrier seal, push in the bolt, and blow some air into the key hole while looking for bubbles around the base of the gas key.

Don't know what kind of buffer, but it was a cheap POS Leapers stock, switched it out with RRA gear I had lying around from another build.  We'll see if that does anything...

My gas key was wiggling around on the carrier when I cleaned the be-Jesus out of the rifle, I nailed it back down, but again, haven't had a chance to get back to the range to check and see.  First time I've ever noticed the gas key getting loose, is there a way to stake it into place?

Quoted: My gas key was wiggling around on the carrier when I cleaned the be-Jesus out of the rifle, I nailed it back down, but again, haven't had a chance to get back to the range to check and see.  First time I've ever noticed the gas key getting loose, is there a way to stake it into place?

So was your Bushmaster twitchy WITH the loose gas key?

Quoted: My gas key was wiggling around on the carrier when I cleaned the be-Jesus out of the rifle, I nailed it back down, but again, haven't had a chance to get back to the range to check and see.  First time I've ever noticed the gas key getting loose, is there a way to stake it into place?

If possible, use new screws.  Torque 35-40 inch pounds and stake in two spots with a punch.

Metroplex, must have been, but now it's nailed down, will follow up with a report after next range session.

Ok, but just FYI: My RRA key was bolted down TIGHT, the screws were staked, etc... And when I did the leak test using my own lungs and a straw, I found lots of bubbles streaming out from the "seal".

I lapped the gas key and used red threadlocker as a sealant.
Tweak's idea is better: He puts light cutting oil on the bolt carrier and rubs the gas key back and forth 40 times and then bolts it together.

I'm guessing that the bolt carrier is machined and the surface should be relatively flat compared to the cast? gas key itself. The gas key is probably more in need of lapping than the bolt carrier. There are lots of machining required to make the forward assist cuts and other parts of the carrier, it makes zero sense for them to leave the gas key surface of the carrier rough.

Good luck and keep us posted. I have a Bushmaster 24" H-bar on a RRA upper with RRA bolt carrier group that short strokes on Wolf. I think we narrowed it down to either too small of a gas port on the barrel (unlikely from what I have read) or the bolt carrier. I do not have a spare bolt carrier to try but just seeing bubbles at Lung PSI makes me wonder if this is indeed the culprit (lung psi <<<<<<<<<<<< rifle gas pressure)

Metroplex

THX, I'll keep the updates going, will try to get out this weekend to troubleshoot more, will check into both fixes/rememdies you relayed.

let me know what works for you, because I am having the same problem with a brandnew bushmaster modular m4 16" that i picked up this afternoon.  how disappointing...
-j

add to edit: plus my bolt doesn't lock open on the last round.

It's funny because a friend just told me his Eagle Firearms AR worked fine on Wolf since day one. And my Bushmaster/RRA rifle is having problems.

i was using pmc

Does it function 100% with XM193/M855?

Call me crazy but I would never use Wolf ammo in any of my ARs. Lake city, Fed, Black Hills, XM193,  UMC, Olympic, SA all run fine. I've heard of too many issues with wolf to even try it. I use Wolf for the AK. Nuff said.

Quoted: Call me crazy but I would never use Wolf ammo in any of my ARs. Lake city, Fed, Black Hills, XM193,  UMC, Olympic, SA all run fine. I've heard of too many issues with wolf to even try it. I use Wolf for the AK. Nuff said.

Wolf will cause short stroke issues in some AR-15s, which is basically what I have seen occur with "high quality" name brand AR-15s using ammo like Black Hills 77gr at certain times!

I believe that if an AR-15 is functioning 100% on Wolf, then it should function 100% on other ammo.

Quoted: This sounds like short stroking to me.  What buffer are you running?  H, H2?  Wolf may not have had enough power to cycle reliably in your rifle.  MJD

This is the EXACT PROBLEM.  I have the same problem with Wolf in my Bushie.  Wolf is just too weak a round therfore isnt forcing the carrier back far enough to allow the next round to be stripped and chambered.  Wolf wont even for my bolt back far enough to the lock position on the last round.  Simple fix dont shoot WOLF.  

I wonder if the lacquer coating does indeed add more friction compared to naked brass or the "polymer" coated steel cases?

Has there been any word from the original poster?

ALCON,

Sorry for the late, late response, got the gun up and running...it was the loose gas key, tightened and staked it into place and ran a shit load of SS109 through it, runs like a raped ape.  

Thanks for all of the help.

P.S.

Have run about 1K rounds through my recent Mutt gun build, and haven't had a single stinkin' problem (Del-Ton upper on Stag lower).

I have experienced similar problems with Wolf in one particular Bushmaster. That rifle works with
XM-193 just fine but will malfunction with Wolf the same way the oringinal poster described.

I have another Bushmaster that works with anything and everything.

Quoted: I have experienced similar problems with Wolf in one particular Bushmaster. That rifle works with XM-193 just fine but will malfunction with Wolf the same way the oringinal poster described. I have another Bushmaster that works with anything and everything.

Get to work on that twitchy rifle!

My AR-15 used to cycle XM193 and M855PD but not wolf. Now it will cycle Wolf and appears to have slight over-action with M855PD.