300blk Ammo Question

[jjones88]

Alright so I took the plunge into the 300blk realm over the 4th of July. Bought a Radical Arms 8.5" upper and stuck in on one of my spare lowers (pistol build).

Bought a couple different factory loads, and some hand loads from TomKat at the Howard County show Saturday. First time out today I ran:

20x Nosler Varmageddon 110gr
20x 150gr FMJ TomKat loads (LC brass)
10x 125 gr TomKat loads (LC Brass)

Noticed a random primer on the bench and started looking at my brass and saw this:



Very odd growth on the Nosler brass. It obviously attempted to expand in the chamber but only on one side? Definitely very hot in my rifle as I had 3 blow the primers out of the brass and then had swipes on every other casing. No noticeable felt recoil difference though. In fact it was during cleanup that I even noticed the primer on the bench. Didn't notice the abnormal brass growth until I got home and started sorting the brass. None of the LC brass exhibited any overpressure signs.

Here are the blown primer brass shots:




Now my question is that the ammo is factory overruns from ShootersPro Shops, is it the chamber in my rifle or the loads themselves? I've got 10 boxes of this stuff (12.99/box over the 4th). Send it all back?

*edit here is the link to the ammo in question:
http://www.shootersproshop.com/nosl...grain-fb-tipped-ammunition-over-run-20ct.html

 

[BradMacc82]

Call Nosler directly.

Almost looks like the pockets deformed as well (although that could be an optical illusion due to angle of picture), but the ejector swipes are definitely there - even though the ones with primers still in them don't show tell-tale pressure signs.

I wouldn't shoot that remaining ammo, if it's popping primers on the Nosler ammo only, then that's enough warning to shelve it until hearing from Nosler.

 

[outrider58]

The primers that stayed in look OK. Can't tell if there's any flow on the brass but, I don't see any in the pics. Case aren't sooty so, no sign of over gas...

 

[BradMacc82]

Brass appears to be weak on second look, if the primers blew out due to over-pressure, there'd be some soot/carbon on the rim from where gas was escaping during the firing.

Looks like it lost those primers during the ejection process.

I'd still call Nosler and let them know you have a batch of suspect/substandard brass and shelve that ammo until they get back to you.

 

[smokey]

You have the upper checked for head space and that the chamber is cut correctly?

 

[outrider58]

I'd still call Nosler and let them know you have a batch of suspect/substandard brass and shelve that ammo until they get back to you.

Agree

 

[jjones88]

Haven't checked chamber, but closed on the go and didn't close on the no-go.

Brass grew at the shoulder by .01" on all pieces checked for the LC brass. Nosler brass falls in line within the standard deviation (~3.087"+-.002" with the Hornady comparator post firing, 3.071"+-.002 pre-firing). Don't want to open another box of Nosler to see where they set their shoulder.

All the primers look fine, but I feel reading primers as an almost wasted effort. Ejector swipes are present on every Nosler casing but not on the LC casings. There was an obvious soot ring around the firing pin on the bolt, but it cleaned right off.

I'll give Nosler a call and see what they say. One thing is for sure, this upper ejects cases violently, my deflector is solid gold now, and the dings at the case mouth are very noticeable. It leads to the theory of defective brass, all primers were found in my brass collector container that I use to toss my brass in from my catching net. Still a super hot load though...

Sucks if its the ammo, bought this stuff to deal with some coyotes / small hogs and for $12/box its a great deal...

 

[jjones88]

Clarifying my measurements, I don't zero once I put on the comparator gauges...

1.075" after firing. Nosler shows their shoulder at 1.071"?

I can't get a good reading on the LC loaded cartridge. The B comparator wants to grab way up so its around 1.058-1.062" but it's reading from a different location.

http://www.nosler.com/nosler-load-data/300-aac-blackout/

 

[Melnic]

Any issues on the tomcat ammo?
My dad uses them and never had an issue with 300BLK including the subs they make.

 

[jjones88]

Any issues on the tomcat ammo?
My dad uses them and never had an issue with 300BLK including the subs they make.

Not a one, a few of the 125's have swipes but the 147 and 220's worked great.

I'm still waiting to hear back from Nosler. I called and they wanted pictures of everything. The more I research, the more I think I'm just overgassed. Ordered an H2 from BCM and just waiting for the white truck to show up with it, should be any day now.

 

[Melnic]

Correct me if I'm wrong but with 300BLK how much gas you get affects if subs work or not. My dad has yet to have an issue with his Hardened Arms upper and it works with both 150gr and 205gr subs. I reloaded for him some and they worked fine. Seems with the variation in 300BLK loads, some uppers may be finicky?

 

[jjones88]

I haven't tried subs (true ones) yet. I ran 220's without a can (starting my trust tomorrow).

That led me to the conclusion of an overgas situation. The faster loads (110 and 125gr) were screaming during ejection (1:00 pattern) and show the bolt swipes / loss of primers (110gr only) and the heavier loads (147 and 220) were more at the 3:00 pattern and show no "pressure" issues on the brass.

Shooting subs with a can should increase backpressure so going to a heavier buffer to cycle the light supers should be okay when I switch to subs.

 

[jjones88]

Heard back from Nosler, their engineering dept? want to take a closer look. They are sending me replacements and taking these back no charge.

+1 for customer service, though I still think I was just overgassed

 

[outrider58]

Heard back from Nosler, their engineering dept? want to take a closer look. They are sending me replacements and taking these back no charge.

+1 for customer service, though I still think I was just overgassed

Hey, it's Nosler.

 

[BradMacc82]

Heard back from Nosler, their engineering dept? want to take a closer look. They are sending me replacements and taking these back no charge.

+1 for customer service, though I still think I was just overgassed

Over-gassed wouldn't cause primers to fall out. That is a fault with the brass or the specific loading of those individual rounds. I didn't see one spent round in your pics that would lead to a high/over pressure round line of thinking.

The ejector swipes, yeah - the upper is a bit over-gassed, but that's relatively easy to mitigate.

Getting a primer stuck in the bolt cam recess and locking up the upper, not quite as easy to mitigate. BTDT with a fellow forum members suppressed 300BLK.

 

[Speed3]

Over-gassed wouldn't cause primers to fall out. That is a fault with the brass or the specific loading of those individual rounds. I didn't see one spent round in your pics that would lead to a high/over pressure round line of thinking.

The ejector swipes, yeah - the upper is a bit over-gassed, but that's relatively easy to mitigate.

Getting a primer stuck in the bolt cam recess and locking up the upper, not quite as easy to mitigate. BTDT with a fellow forum members suppressed 300BLK.

I know who I'm coming to if I have issues with my 300 lol.

 

[DaemonAssassin]

I know who I'm coming to if I have issues with my 300 lol.

Brad knows his chit.

 

[jjones88]

that's why I posted here! Figured with enough members playing in the 300blk game someone would have some advice