Welcome to SMIArms.com, a division of Signature Manufacturing.


0 item(s) - $0.00
You have no items in your shopping cart.
Swipe to the left

300 blackout myths and subsonic ammunition

By Mike Everhart 1 years ago 557 Views No comments

With all of the content out there on the internet, I am always amazed by the incorrect information I see out there. 300 blk along with 300 whisper were primarily designed to shoot subsonic ammunition while suppressed. Let me repeat that "while suppressed". We have dealt with many customers who contact us with "issues" regarding 300 blackout guns. Almost all of the problems revolve around subsonic ammunition that the gun owner is attempting to fire without a suppressor.

Essentially, the lower pressure subsonic round does not have enough back pressure via the gas tube to fully drive the bolt carrier group back far enough to allow the bolt to strip another round off of the magazine to load into the chamber. Another sign of this low pressure is that the bolt often doesn't lock back on the last round. Once again, this is because of the lower pressure of the sub-sonic round. There can be more serious consequences of using this ammo without the suppressor. depending on the cartridge load, you can potentially lodge a bullet in the barrel which can lead to all kinds of nasty surprises. Trust me, you can do without those surprises. Putting a suppressor on the same firearm greatly increases this "back pressure" and causes the bcg to function normally. Remember, the 300blk cartridge is a 223 case that has been cut off and re-necked for a 308 bullet. You don't have to change the bcg, You only need to change the barrel or swap uppers to have a new gun.

Here are a couple of ways to "fix" the issues with 300 blk ammo and guns:

1. don't use subsonic ammo without a suppressor! Instead, use hypersonic or supersonic ammo and you shouldn't have a problem.

2. increase the size / diameter of the gas hole in the barrel (don't exceed the gas block hole size). This can be a problem if you later attach a suppressor.