Bad ammo or something else

[JB62]

Had a chance to take a new build to the range on Sunday and after playing with adjustable gas block ran great. Shot Hornaday and some wolf gold.

Rifle is 6.5 Grendel ar with Odin barrel and bolt.

Was looking through some of the cases this evening as eventually want to get into reloading so keep majority of brass.

Found an interesting case from the wolf and was shot suppressed. Slow fire as ammo is too expensive and was trying to work some kinks get used to rifle.

Is this an ammo problem or rifle problem. Did not think an ar could shoot OOB?

 

[Squaregrouper]

Looks like it was fired OOB.
I own two AR Grendels and have never had that happen.

 

[JB62]

That is what looks to me as well however thought the way an ar bolt was designed would not allow to fire out of battery.

Maybe firing pin too long allowing it to happen?

 

[Ski169]

Check headspace?

 

[JB62]

Have not, will be ordering gauge. First ar in this caliber.

 

[JB62]

More I look at cases think it is brass issue.

Hornaday left / wolf ppu right

 

[Rocinante]

Your PPU brass is not properly sealing. Given the extra backpressure from your suppressor, your dwell time may not be long enough.

Also Odin had a 6.5 recall a few years back. Also check to make sure both your extension and BCG are both either Type 1 or Type 2 as mixing them will also cause problems. A Type 1 has 0.125" boltface depth, and a Type 2 has 0.136" depth.

"Dear Primary Arms Customers,

Odin Works contacted us about an issue affecting some of their 6.5 Grendel barrels. We are passing this important recall information to you because our records show you purchased an Odin Works 6.5 Grendel barrel that could be affected. There is an easy way to check your barrel yourself without any tools.

Using a new piece of 6.5 Grendel ammo or brass, insert it backwards into the chamber. DO NOT PUSH hard. Used brass pieces can give false readings. DO NOT PUSH hard. If the whole piece of brass drops in, you have a bad chamber. If half the brass is still sticking out, you are good to go."

 

[Squaregrouper]

More I look at cases think it is brass issue.

Hornaday left / wolf ppu right

This is not a brass issue. Look at the neck on the blown out brass. It was clearly fire formed.
I am a Grendelphile and a reloader, but not an AR expert.
Is it possible that it was over gassed- which would move the bolt rearward before the chamber pressure was reduced? Suppressed shooting would amplify this problem.

 

[JB62]

Could very well be an overgassed issue reducing dwell time. I am not an ar expert by any stretch and first adjustable gas block of this type which was still trying to get dialed in so may have over adjusted.

Only other adjustable gas block I have has settings which make it much easier. This Odin is just Allen key with no indentations or other positive means of adjustment confirmation.

 

[JB62]

Thanks rocinamte, good information and will have to test that out tomorrow. New purchase but had no idea about the recall so will make sure not new purchase of old stock.

 

[jrumann59]

on an unfired wolf check the overall diameter of the case. Maybe the cases are a little big and not making it all the way into battery.

 

[Melnic]

Don't let anyone ever say an AR can't have OOB, things can go wrong.
My opion is that it started to eject before the pressure was reduced to safe levels.
If you did not feel anything strange when shooting it, that is what I feel happened.

I had an incident where mine had a double ignition (I pulled trigger once and 2 fired).
In my case I blame a high/defective primer that ignited when the firing pin moved forward with the bolt and bolt bounce along with some worn bolt lugs (bolt was from a Vietnam M16 Kit so it was well worn) cause it to prematurely start to exit before pressures reduced.
Like yours, I had a bulge (mine was worse) and the shoulder moved forward (like yours appears to be).
In my case I could instantly tell (2 for 1) that something went wrong and started to inspect things in addition, stop shooting it for the day.

 

[jrumann59]

Had a chance to take a new build to the range on Sunday and after playing with adjustable gas block ran great. Shot Hornaday and some wolf gold.

Rifle is 6.5 Grendel ar with Odin barrel and bolt.

Was looking through some of the cases this evening as eventually want to get into reloading so keep majority of brass.

Found an interesting case from the wolf and was shot suppressed. Slow fire as ammo is too expensive and was trying to work some kinks get used to rifle.

Is this an ammo problem or rifle problem. Did not think an ar could shoot OOB?

maybe its the pic or an optical illusion but the rim on the possible OOB round looks to wider than the other.

 

[Rocinante]

Thanks rocinamte, good information and will have to test that out tomorrow. New purchase but had no idea about the recall so will make sure not new purchase of old stock.

A thought to expand on since my first post was already lengthy with the images-
if it's not the barrel or bolt and the Hornady fires fine but the PPU is not sealing, this makes me think PPU is a higher pressure round than the Hornady, the PPU projectiles are thicker and have a better seal, or the PPU projectiles are WAY heavier than Hornady. Which ever the case I suspect this likely comes down to your backpressure and dwell time exacerbated by the suppressor.

You also never mentioned what barrel length and gas system you're running.

I have very limited experience with any 6.5x39, but my understanding is it's designed as a mid-to-long-range cartridge (i.e "how can I shove a .308 into an AR-15?") and performs best out of an 18"+ with a rifle gas.

Easiest way to confirm it's not the ammo: load 4-6 rounds in a mag, half Hornady and half PPU and just fire them off without the suppressor, then repeat with the suppressor reinstalled. If the brass is fine without the suppressor and is still bulged and dirty with it back on, it's backpressure + dwell time and you will either need to feed it specific ammo or run an adjustable gas block with the suppressor.