AR not chambering round

[blindnoodle]

What would stop the bolt carrier from chambering a round in an AR?

When I slap the bolt release the bolt slides forward, picks up a round and goes to chamber but stops 1/4 inch short. Forward assist doesn't help.

I have tried a different bcg, magazine, and ammo with no differences.

Friction problem? Buffer spring problem? Trigger group issue? Anyone have any ideas?

 

[Russ D]

I'm worried its the barrel extension.

 

[Topher]

Might be a silly question, but is everything nice and clean???

 

[blindnoodle]

Might be a silly question, but is everything nice and clean???

it had been 20 rounds since the last full strip cleaning. After those 20 rounds it got a wipe down.

 

[herr.baer]

Does your bolt close with out a round in it?

 

[marko]

Ow! Whoa. Headspace ok? Or, does your cam rotate properly?
In the Brownells video, their reinstall of that cam is WRONG!!! .

 

[blindnoodle]

Does your bolt close with out a round in it?

Yes, problem is intermittent. 36 rounds went downrange through it today.

Ow! Whoa. Headspace ok? Or, have you rotated the cam properly?

Yup and yup.

Keep em coming guys. I haven't thought of much of the stuff you've asked!

 

[Russ D]

I checked the bolt out to make sure it was rotating properly.

 

[Topher]

If it closes without a round in it, have you checked the ammo?

 

[blindnoodle]

If it closes without a round in it, have you checked the ammo?

used LC brass with Hornady 68 grain bullets, then federal factory ammo. Same problem with both.

 

[gunconnection]

Are you experiencing the problem with more than one magazine?

 

[blindnoodle]

Are you experiencing the problem with more than one magazine?

yup 20 rd c products, 30 round d&m, and one russ had.

c products had magpul follower, 30 round had a orange follower.

 

[Russ D]

I had a GI mag with Green follower.

 

[blindnoodle]

and the plot thickens...

2 dummy rounds. Both LC brass. Both 2.248 OAL. one has a 55 gr vmax, the other has a 68gr BTHP Hornady match bullet.

BCG operates fine on the vmax, not on the match...

 

[Onua]

check the chamber by dropping a round of each different type in the chamber and seeing if it gets hung up in there?

 

[blindnoodle]

It's the bullet. I guess the wylde chamber doesn't like fat bullets. The rounds I tested has rifling marks.

Tomorrow I'll test it against another gun with the same make and chamber barrel. If mine doesn't eat the same ammo as that one I'll be one pissed off camper.

 

[guthook]

My LMT (5.56) did the same thing when chambering M855, everytime. The M193 chambered without a hitch.

I sent it back to LMT, they put a new barrel on it, problem solved. They didn't tell me what the problem was. It might be a chamber or maybe just a throat issue with the longer bullets? I don't know the inner workings as well as some on this board.

 

[3rdRcn]

I have a RRA with the wylde chamber and it feeds everything including 75 grain, doesn't shoot it worth a shit but it feeds. Maybe take the bolt apart and make sure you don't have anything going on inside. If it fires the ammo intermittently then I would be taking the bolt apart to see if there is something inside causing it to not rotate properly.

 

[hole punch]

ah, Wylde chamber. So it's a tighter fit then a mil-spec 5.56? Is that the problem?

 

[alucard0822]

I have a RRA with the wylde chamber and it feeds everything including 75 grain, doesn't shoot it worth a shit but it feeds. Maybe take the bolt apart and make sure you don't have anything going on inside. If it fires the ammo intermittently then I would be taking the bolt apart to see if there is something inside causing it to not rotate properly.

Same here, I have ARs with Wylde and mil-spec chambers, and they all feed just about anything, including some match loads too long to fit in the magazine. I have had problems before with a barrel extenion in a 16" carbine that had a similar problem, turned out that a combination of a weak magazine spring(allowing the case to be pushed down into the mag a little and hitting the bullet guide at a steep angle), and too narrow bullet guides that were gouging the crap out of some cases heading into the chamber, where they wouldn't seat fully, I sent the barrel back, got one that had noticeably larger and smoother bullet guides, and the problem was solved. If a round won't feed check it to see if it is gouged, dented or damaged in any way, there is also the possibility there is something out of spec in the chamber, either the leade was cut too short, a burr, or if this rifle is not new, buildup on the bolt face and in the chamber itself can effectively decrease headspace to where some ammo won't chamber.