Failure to go into Battery

[BushmasterFanBoy]

Tested it out today with some XM193, same ammo as last trip, and my o-ring removed. This time it only got worse. Had two almost back to back towards the end of my 240 round string of fire, just as the last batch did, with the minor difference that this time the extractor claw caught the case once and I was able to perform a quick clearance drill and keep up my fire. It pretty much went like this on my last mag *bang-click-rack-bang-bang-click-remove mag-rack-reinsert and close bolt-bang-bang-bang ad nauseam*. I used a newer action spring that measured in-spec at a tad over 11", I'm begining to doubt this ammo in my rifle, or should I look into a Wolff higher power action spring?

[Robb Jensen]

If you have one try another bolt.

[BushmasterFanBoy]

If you have one try another bolt.

I have another one, and I'll plop it in, any reason this may be it?

[Robb Jensen]

I have another one, and I'll plop it in, any reason this may be it?

Sometimes certain bolts fits certain barrel extension better. Just variations in tolerances.

[Ridgerunner665]

I don't know much about anything...but if the Oring didn't help....

It seems to me something has to be binding the extractor...is your carrier cracked....or maybe the extractor itself. If so it may be flexing, which might cause your problem.

Or maybe that spring is just too stiff...no 2 guns are alike (I learned that from 1911's)

Just a thought...from somebody who's still learning (and I got a long way to go)

[BushmasterFanBoy]

Sometimes certain bolts fits certain barrel extension better. Just variations in tolerances.

Hmmm, would that still be a possible issue with a relatively high round count upper? This upper has had over 5,000 put through it so far since 2006. It may not be much, but I'd expect teething problems like this to be done and over with?

[Ron S.]

That's nearing the end of a barrel's life at that many rounds, but the upper should be fine.

[BushmasterFanBoy]

That's nearing the end of a barrel's life at that many rounds, but the upper should be fine.

5k is the end of a barrels life? I've heard how the AMU guys ditch barrels at insanely low round counts, but IIRC, I thought most barrels will sustain decent accuracy to 10 or more thousand rounds?

Anyways, with this high of a round count, obviously past the break-in period, but well within the life of the upper, should I be looking more at possible broken/failing parts than anything else?

I've done a check on the BCG, my bolt shows no signs of cracks, and my extractor is still good. All my lugs are in perfect shape, and a quick inspection of my barrel extension/upper shows nothing out of the ordinary.

Is there a possibility this could be ammo related? This failure has been non-existant since I began to shoot this batch of XM193-A. I've shot 5.56 pressure ammo before just fine, for larger round counts in more compact times as well.

[Ridgerunner665]

Is there a possibility this could be ammo related? This failure has been non-existant since I began to shoot this batch of XM193-A. I've shot 5.56 pressure ammo before just fine, for larger round counts in more compact times as well.

If you still have them...mic the rounds that it choked on.

Measure the rim diameter.

[BushmasterFanBoy]

If you still have them...mic the rounds that it choked on.

Measure the rim diameter.

Darn, I had issues just finding the one of them, which I promptly shot, the other got lost in the grass somewhere. On the plus side, I do malf. drills like second nature.

If I did have them, what would I be looking for?