testtest

Why Your .300 BLK Won’t Work…

David N.

Custom
Founding Member
Wow, I never realized that the grain weight also increases the overall length of this cartridge selection. I hunted with 210 grain .30-06 and switched to 165 grain for a flatter trajectory, but I never did a comparison on cartridge length.
 

HansGruber

Professional
Wow, I never realized that the grain weight also increases the overall length of this cartridge selection. I hunted with 210 grain .30-06 and switched to 165 grain for a flatter trajectory, but I never did a comparison on cartridge length.
There may very well be little to no difference in those two; the .30-06 has enough case volume that the heavier bullet can be seated deeper...where .300AAC doesn’t have the volume, requiring the heavier bullet to be seated further out, leading to a longer OAL.
 
Are you trying 556 upper change, not chainbering 556 in a 300bo? Unwise! Function testing full auto against 300bo and 556 or what exactly?
He tried F/A with 300 BLK, it jamed after 3 rounds in a 300 complete upper assembly.
He’s got full auto, does he?
Hans he has a full auto AR15, registered and all. I gave him a 300 BLK 10.5" complete upper assy with 30 rounds of subsonic 300 AAC in a ar15 30 round magazine. I was curious if it would work with 300 AAC ammunition. He responded that it jams at 3 rounds. I don't have the availability to do what he can. He has a shooting range in Nevada. I just wanted to know it everything would work.
 

HansGruber

Professional
He tried F/A with 300 BLK, it jamed after 3 rounds in a 300 complete upper assembly.

Hans he has a full auto AR15, registered and all. I gave him a 300 BLK 10.5" complete upper assy with 30 rounds of subsonic 300 AAC in a ar15 30 round magazine. I was curious if it would work with 300 AAC ammunition. He responded that it jams at 3 rounds. I don't have the availability to do what he can. He has a shooting range in Nevada. I just wanted to know it everything would work.
.300 subs need more gas to be reliable...likely problem.

Usually, just attaching a suppressor will take care of it, or opening up the gas block, if it’s adjustable.
 

10mmLife

Professional
Founding Member
Never had a problem shooting .300blk using pmags with 125gr up to 240gr ammo

.300blk is my favorite intermediate rifle round to shoot, especially when suppressed!
 

TEXASforLIFE

Hellcat
He tried F/A with 300 BLK, it jamed after 3 rounds in a 300 complete upper assembly.

Hans he has a full auto AR15, registered and all. I gave him a 300 BLK 10.5" complete upper assy with 30 rounds of subsonic 300 AAC in a ar15 30 round magazine. I was curious if it would work with 300 AAC ammunition. He responded that it jams at 3 rounds. I don't have the availability to do what he can. He has a shooting range in Nevada. I just wanted to know it everything would work.
What brand and cartridge of mags is he using? I don't have any 300bo mags, just 556. I'll reload some 185 - 240gr and check function with the 556 mags( lancer, pmag, hexmag and whatever else I have)?
 

TEXASforLIFE

Hellcat
He tried F/A with 300 BLK, it jamed after 3 rounds in a 300 complete upper assembly.

Hans he has a full auto AR15, registered and all. I gave him a 300 BLK 10.5" complete upper assy with 30 rounds of subsonic 300 AAC in a ar15 30 round magazine. I was curious if it would work with 300 AAC ammunition. He responded that it jams at 3 rounds. I don't have the availability to do what he can. He has a shooting range in Nevada. I just wanted to know it everything would work.
Low powder charge with heavy bullets might have the pressure, but not the volume of gas. Burn rate vs gas volume produced. I don't run subs in my 300bo even with the 8.5" barrels or have suppressors. I've been saving my heavy 30cal bullets for my 300wm (190+ gr).
 
Top