i was running a suppressed 10.5 LMT barrel and an ACOG and appear to have a couple end cap strikes in my m4-2k when using prvi 75gr match ammo. i was getting good accuracy all the way out to 400yds though.

so my question is.......could it be inconsistent bullet construction causing this or is it a common event with  heavy bullets in 10.5's?

i considered using a 11.5 or 12.5 barrel to eliminate bullet instability for this set up. i still want to use the ACOG and the suppressor so will the 11.5 or 12.5 help me out? or should i lighten up my bullet weight to ensure no more dings?

thanks in advance.

I've shot over a thousand rounds of 75gr ammo in multiple 10.X inch barrels and have never had a baffle strike.

Could it be that your can is not concentric to the barrel?

what ammo?

pretty sure its concentric considering its LMT and AAC stuff but i havent checked.

i was thinking its just cheaply made bullets that might not be perfect in design and not flying straight. priv 75 gr is good but not that good, overall.

Ill echo I haven't had a problem using heavy stuff out of a 10.5 with a 1-7 twist.

I did have a end cap strike recently as well though. It was using 55 grainers. I guessing I just got a bad round. Took several years and several several thousands of rounds to finally have one on my M4-2000 so I guess I cant be too mad.

I have not used privi however

You sure you had the can all the way locked down? I almost wonder if I didn't get mine all the way tight as I was moving it to different hosts while it was pretty hot and may not have locked it down all the way. Who knows though.

AFAIK the can was seated all the way down but mine is the old 18T mount and they are not quite as tight as the new stuff. i have a habit of running mine on the last full notch, even though you can titghenmore and get a half notch situation...know what i mean?

wonder if that tiny bit of wobble the 18T has makes a difference?

the strikes dont bother me too much, just dont want to make a habit out of it!

Nah I understand what you are saying. I have some mounts tighter than others. Here is what I do. I tighten it all the way down, and then back it off not holding the latch so it will then hit the "wall" of the tooth. I understand you don't have the latch on the older can, but I basically do the same as you I believe. I hope that makes sense.

Could have been anything man. After talking with AAC on my end cap strike they told me basically if I use it as much as I said I did then I was lucky it didn't happen before. Apparently end cap strikes just happen. They told me a bad round was likely the culprit. Im not sure if it was the host(which was a new one, HK33 clone) with bad threads, a bad round, me not getting it all the way tight, or what. I have since just tried to move on. I don't use it on that host much anymore, but have a little with no ill effects. They told me if I had bad threads I would have noticed pretty immediately upon firing. The fact it didn't happen right away on the new host leads them to believe the issue lies with a bad round

I have just tried to move on with it. I was kinda pissed when it first happened. But it has no ill effects on accuracy and you cant really tell to be honest. I almost wonder if it has happened before. I have a shit ton of rounds through mine and there were small chunks missing from the inside of the end cap from before but I thought it was just erosion. This end cap strike I had recently actually raised the metal a tid bit and is clear a bullet kissed it pretty good. I was told by a ex AAC guy they can chop the old end cap and weld on another if it needs to happen due to inconsistent accuracy

My main host is a 10.5 gun and it has never given me any problems, other than the small chunks missing from the inside of the end cap. I still think that maybe erosion however.

I have heard the older cans can suffer from coming loose under firing. Ever noticed this happening before?

yep, makes perfect sense and i dont fret it much either. they are tools and tools get used.

i get a little wobble but i have never had it actually back off a notch and i have 3 different AAC cans with 18T, an m4 2k and two of the old shorty SCAR-SD cans.

i'll probably switch to a 11.5 or 12.5 for the heavy bullet stuff and see if i get any more strikes with the prvi 75gr. i have 1500 more rounds so i should be able to tell by then!!  

thanks

If you are worried about stabilization that's an easy test buddy.

Just remove the can and shoot at a distance unsuppressed and see if the holes look circular on the target or not.

I really don't think the stabilization is the issue as long as your barrels are 1-7 which I believe the ones you listed are.

But good luck any way you go about it. I had a 12.5 for a long time and I loved it. Hornady superformance 75grain 5.56mm was the death of that upper however. The lower survived the KB thank god

super performance had a KB? i didnt think it would even run in anything under 20" barrels?

Yea I guess I was the only one out of that loop. I had no idea you weren't suppose to. And it didn't run, first round blew it sky high

wow, still weird. i just heard that it wont cycle the action since the powder was a slow burning one that didnt generate enough peak pressure.

The problem with the short barrel and suppressor was it help pressure too long, coupled with out of spec brass per hornady.

They sent me some free ammo. Im not mad about it. I should have pushed for more though