What happens when you're 2.5gr over max in .300blk

Ikarus1

Avtomat Krishna-kov
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No, not a kaboom this time thankfully. I attribute that to the shorter bull barrel of my .300blk AR pistol, and the fact that the cartridge is spec'd at a much lower pressure than the 5.56 bolt and AR type action is capable of handling. Also I am glad I had a H2 buffer to tame some of the recoil of the very overpressured round. I also was loaded the rounds to a OAL of longer than spec (since there's room in the mag up to 2.300 or so



The gist of it is this:


I mixed up the projectile boxes and though I was loading 125gr Nosler BTs. I did it late at night (mistake #1), I didn't read the box and assumed because it had a nice little green tip (for .308 cal) that it was correct.
The next morning I went hunting, took a shot on a little 3 point cull buck at close range, and lost the deer.
So as I was going thru everything, I took the gun over to the steel plates and the rounds were louder than usual, had way more recoil than I recall, and the brass started sticking and causing extraction issues.

I didnt immediate inspect the brass but when i did I found the blown primers.



I was loading 168gr pills at 17.5gr of H110. The max for that weight bullet per the Hornady manual is around 15.
Primers blew out of the shorter COAL rounds I had loaded, and I had ejector and extractor swipes on the case.

When i disassembled the BCG i found a primer had lodged itself in the piston area.

Lessons were learned. Glad it wasn't the hard(er) way.
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Thanks for the honest, no BS, evaluation. It always helps to have real world examples to remind us why we need to be cautious.

Yes I really gotta thank God that myself nor my shooting buddy was hurt. He said “man that thing is loud” even with ears on outdoors and I recalled when I shot the deer that it made my ears ring like a .357 magnum. I got a lot of chances to figure it out before it injured someone.
 
Reloading, Scuba and skydiving all have big safety margins built in...
I can't imagine why!! ;)

Tape one of those blown primer rounds above your reloading bench.
Good reminder.
Take a plastic ammo tray from a factory box of ammo and stick all that brass in it. Use that block as a paperweight on the bench.

Just like powder, keep only one kind of bullet that you are loading on the bench. Know the weight and know your load data.

Sent from my SM-J320V using Tapatalk
 
Odd that it did that. I guess calibers handle it different . Books usually post low numbers. I'm 2.5+ over what the book says for my 6mm and 6.5 and shoots find, could go even higher if I wanted to without issue.
 
Odd that it did that. I guess calibers handle it different . Books usually post low numbers. I'm 2.5+ over what the book says for my 6mm and 6.5 and shoots find, could go even higher if I wanted to without issue.
There's not much room in the .300blk case for a 168, and I was loading close to max (which is 18gr). The percentage is more important than the amount you're over. In this case, it was a 14% overcharge. And H110 magnum pistol powder burns a hell of alot faster than any rifle powder. I literally built little grenades lol.
 
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This is probably one of the main reasons I don't reload.

I know myself and my limitations.

I could start something and have laser focus but after a few sessions, I'd most likely overestimate my skill set start losing focus.

I don't shoot enough either for reloading to be a cost effective option.

It was a fluke. The bullets had similar overall appearance right down to the green tip, and the .300 is a low pressure round (same 35K PSI as a 9mm/40). Thankfully, the AR bolt is spec'd to handle much higher pressures. And if you had to pay for premium .300BLK hunting ammo, you'd definitely learn how to reload if you shoot it much. I don't have any regrets....I started out loading H110 in the .44 magnum once I learned how much that ammo cost.

My next adventure is arriving this week in the form of .300blk's big brother, the .458 socom :D
 
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This is probably one of the main reasons I don't reload.

I know myself and my limitations.

I could start something and have laser focus but after a few sessions, I'd most likely overestimate my skill set start losing focus.

I don't shoot enough either for reloading to be a cost effective option.

It's why I don't reload as well. I do not have the patience in most things to ensure safety protocol for what amounts to mindless work for the most part. I know it. I'm the guy that reads the directions on second coat time for spray paint and then immediately ignores them because I want it done now, not 10 minutes from now.

So yeah, reloading is not in the cards for me.
 
ok homos go back to the basement with that it's not queer if it's on the pier stuff :D

Meanwhile, reloading aint for everyone. Definitely if you can't read the damn box at 12:15am the night before you're hunting with the ammo you're making. Even if you know the recipe by heart.
 
There's not much room in the .300blk case for a 168, and I was loading close to max (which is 18gr). The percentage is more important than the amount you're over. In this case, it was a 14% overcharge. And H110 magnum pistol powder burns a hell of alot faster than any rifle powder. I literally built little grenades lol.
ah makes sense! I didnt think about the size of that bullet in that tiny case. glad youre ok
 
Thanks for posting the story. Glad you didn't blow up :).
 
Just think, 10% over would have probably been just fine at this COAL and charge I believe.....and the load was pretty damn accurate and powerful [emoji23]
 
Thanks for the excellent examples of what blown primers look like (duh), extractor marks, flattened primers, and firing pin cratering. I am printing those pics to have in the load development kit.

Glad you didn't load 2.6 grains over!!!!!

Thanks for the write up. Keeps us all careful.
 
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