blown primer in factory fgmm 6.5cm ar10 question

[rockwind1]

situation: hoping this isn't a stupid question. maybe just the gas block.
bought a very low round count ar10, decent components, Criterion 16 inch barrel. JP matched high pressure bolt. JP silent capture springs. Rise Armament Trigger, unknown adjustable gas block,

anyway,, when i got it, i put a 338ba suppressor on it that i wasn't using, and used fgmm 6.5 factory 130 berger hybrid OTM ammo. i put 10-15 thru it with a trij mk3 and then got squirreled. it shot great and no probs. 2 years later, circumstances made me want to revisit it, but i put on a ultra 7 .30 cal suppressor. I don't remember dicking around with the gas block last time. anyway,, it seemed like a lot more gas than usual went in my face but i didn't remember exactly from 2 years ago so, i shot again and it didn't cycle right. looking in the mag and found a blown primer. so i think it clogged up the mag. i picked up the 3 cases and sure enough a blown primer, also the primers look a little flat,, and decent marks on head.

i know ar's are pretty hard on cases but having a blown primer seems extreme. my thoughts are maybe the smaller suppressor caused more gas build up,, perhaps i should adjust gas block but it still seems a little weird, it's just factory federal ammo, how hot can it be?

appreciate any thoughts. merry christmas to all!

 

[Doom]

As your post elsewhere has indicated you have a big pressure issue. The ejector marks are the telltale. Reading primers is something that is problematic when it comes to factory ammunition. You don't have a reference beyond the rounds in the box. A reloader is shooting increasing loads so he/she can compare changes and get a feel for what is happening.

It appears all the rounds in the picture have gas leakage in the primer pocket. I would call Federal and discuss what is going on here. You might have a rifle issue but I honestly believe this is an ammunition might be at issue.

 

[rockwind1]

As your post elsewhere has indicated you have a big pressure issue. The ejector marks are the telltale. Reading primers is something that is problematic when it comes to factory ammunition. You don't have a reference beyond the rounds in the box. A reloader is shooting increasing loads so he/she can compare changes and get a feel for what is happening.

It appears all the rounds in the picture have gas leakage in the primer pocket. I would call Federal and discuss what is going on here. You might have a rifle issue but I honestly believe this is an ammunition might be at issue.

yes, i have been gathering more info, I suspect this ammo is just to hot for this rifle, I am looking for some factory 6.5 cm ammo that is hopefully loaded below sammi specs. someone suggested hornady black. i'm not a hornady fan but seems like easiest solution.

 

[John Glidewell]

Have you tried any other factory ammo besides the Federal? Can you take a couple of those apart and weigh the powder charge? I would also look at the factory crimp, might be obvious over crimping you can see.

 

[rockwind1]

Have you tried any other factory ammo besides the Federal? Can you take a couple of those apart and weigh the powder charge? I would also look at the factory crimp, might be obvious over crimping you can see.

i have not yet, next on the list. i wasn't trying to re-invent the wheel on this,, i have posted asking if anyone knows of an existing factory cartridge that is kind of well known to work in an ar10 6.5. i guess i just trust federal to not over crimp their match ammo.

 

[6.5SH]

Have a borescope? What does the chamber and throat look like?

 

[rockwind1]

Have a borescope? What does the chamber and throat look like?

i do somewhere, gotta dig it up. also on the list. since it is not working, i got squirreled and am using my 308 now, but will check out all ideas!

 

[Rocketmandb]

Do a search on something like "suppressor overpressure" and see what comes up.

 

[nn8734]

i have not yet, next on the list. i wasn't trying to re-invent the wheel on this, i have posted asking if anyone knows of an existing factory cartridge that is kind of well known to work in an ar10 6.5. i guess i just trust federal to not over crimp their match ammo.

Federal brass in 6.5CM has less case capacity than other manufacturers from what I've seen so if your rifle is aleady pressure sensitive, anything in Fed brass prob pushes it over the edge.

Had this problem when reloading using fed brass in my AXMC proof 6.5 cmoor barrel and couldnt get more than 40.5 ish grains of powder in the case before hitting pressure using 130 otm hybrid brgrs. Switched to Lapua srp brass and got 42.4 and an extra 100 fps or so with better precision. Maybe try some Hornady ammo or start reloading.

 

[Cr1775]

Have you tried any other factory ammo besides the Federal? Can you take a couple of those apart and weigh the powder charge? I would also look at the factory crimp, might be obvious over crimping you can see.

Weigh the powder all you want, but witch powder are you weighing?
Before I'd do that I'd ask Federal what powder they use good luck with that.