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300 AAC Blackout Flame Thrower - Need Help!

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markr6754

Elite
Founding Member
Okay .300 AAC Blackout loaders...I made up a box of rounds using 120gr Powerbond bullets, 14.7gr H110, S&B SRP, seated to 1.900”. They fired and cycled well through a new build 7.5” AR Pistol, as well as my previous 10.5” AR Pistol. Loaded from multiple magazines, shot well, bolt lock back every time.

That all anyone could ask for, right?

Okay, so besides the massive BOOM these puppies made, there’s the issue of the massive fireballs that extended 12” in all directions...to include back towards me!! I could feel the heat in my face, along my bare left forearm, and it was truly blinding in our indoor range. I really wish I’d had a camera rolling because it had to be an impressive sight...just not one that I want to repeat. My son, a disabled marine veteran wouldn’t shoot anymore after the first 10 rounds. I’m past Medicare age, somI figured...what the hell! I sure wasn’t willing to spend the time breaking them down.

Is this normal? It was my first negative experience with the 300 Blackout.

Suggestions, or just give up on H110?
 
markr6754 said:
Okay .300 AAC Blackout loaders...I made up a box of rounds using 120gr Powerbond bullets, 14.7gr H110, S&B SRP, seated to 1.900”. They fired and cycled well through a new build 7.5” AR Pistol, as well as my previous 10.5” AR Pistol. Loaded from multiple magazines, shot well, bolt lock back every time.

That all anyone could ask for, right?

Okay, so besides the massive BOOM these puppies made, there’s the issue of the massive fireballs that extended 12” in all directions...to include back towards me!! I could feel the heat in my face, along my bare left forearm, and it was truly blinding in our indoor range. I really wish I’d had a camera rolling because it had to be an impressive sight...just not one that I want to repeat. My son, a disabled marine veteran wouldn’t shoot anymore after the first 10 rounds. I’m past Medicare age, somI figured...what the hell! I sure wasn’t willing to spend the time breaking them down.

Is this normal? It was my first negative experience with the 300 Blackout.

Suggestions, or just give up on H110?
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That's definitely not normal for a .300blk round and I would be concerned about the chamber pressure.
 
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There is a possibility that not enough powder was burned before the bullet exited the barrel. If the primer is still seated and the case is undamaged try using cci450 as for that is what I use for h110, ww296 and lil'gun in my 300bo! Magnum primers for magnum powders as for the intent. A reduced powder charge will be required when going from standard to magnum primers because of more pressure with the magnum primers!
 
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TEXASforLIFE said:
There is a possibility that not enough powder was burned before the bullet exited the barrel. If the primer is still seated and the case is undamaged try using cci450 as for that is what I use for h110, ww296 and lil'gun in my 300bo! Magnum primers for magnum powders as for the intent. A reduced powder charge will be required when going from standard to magnum primers because of more pressure with the magnum primers!
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Primers were fine, cases were fine, cases ejected normally...no excessive force/distance. I cleaned and resized/deprimed the cases last night and it took very little effort, as if the cases hadn’t been altered by the experience. These were Speer Nickel cases that I cut down for .300 Blackout. Beside easy sizing/loading, they look purty!
 
TEXASforLIFE said:
The 300bo reloading thread mostly between myself and SmsgtRod has the pics.
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Yeah..I was involved in a few threads. Then got caught up developing pistol loads for my wife...finally got her into .380 ACP shooting, with a touch of soft 9s now and then. But I just built a new 7.5” AR pistol with my son...his first...and she insisted I take him out to shoot. I’ve missed my 300 Blackout time. I actually made up these loads in May and just now got out to test them. Aside from the fireball rounds we ran some heavier 4227 and VV N120 loads. All I noticed there was some light sparking out of the muzzle on the 4227 loads. Nothing worrisome at all.
 
krunchnik said:
Possibly running about 4.0 grains lighter than listed-could be not enough pressure to fully burn the powder-just reaching here but most the loads I am finding is around 18.0gr.
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I’m having a bit of a challenge actually finding loads for 120gr Powerbond. Every manual I find has loads for 110gr or 125gr, so I was flying by the seat, as they say.
Thanks for the response. It looks like a small, 5 round group would be a smarter place to start, if I attempt H110 again. Additionally, I could add SRM primers to the test, as I actually have some on hand.
 
EPIPHANY.....

I checked all of my load sources to determine how I came up with 14.7gr, which is well below all starting loads for 110gr and 125gr bullets.

Then I went to my Stevespages.com account and found a potential answer...and a reminder of why we write down, print out, or highlight recipes during loading.

300 Whisper (Blackout)
110 gr Projectiles
H110 16.3gr to 20.4gr
N110 13.6gr to 19.0gr

125gr Projectiles
H110 14.9gr to 19.0gr
N110 13.7gr to 17.7gr

I must’ve glanced at the page while setting my recipe and picked up the wrong line! It makes sense when I try to rationalize a 120gr bullet over 14.7gr of powder. In both cases it’s a grain higher than the starting load for VV N110.

Appreciate the feedback which forced me to dig deeper for the reason behind my error!
 
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