300 BLK - 9" vs. 12.5"

[ny32182]

I have been unable to locate a discussion on the exact tradeoffs between these two barrel lengths, other than some subsonic velocity numbers. As expected, there is very little velocity difference between the two with subsonics. What I am curious about:

-What is the velocity difference with supersonic loads?
-Is there any notable reliability difference between the two (example: will 12.5" be notably more reliable with subsonics and no suppressor?)
-Is there likely to be any real difference in suppressor lifespan between the two?

Has anyone shot significant numbers of rounds through both? Thanks.

 

[C-grunt]

I have been looking at similar barrel lengths. From what I have seen the difference in super sonic loads should be about 100-150 FPS. It was specifically designed for the short barrels so you dont see a huge jump in muzzle velocity when you go longer. Not sure on the other questions. I have read though that because the 300 BLK is a lower pressure round that its pretty easy on suppressors.

 

[Z-Michigan]

You'll find most 300BLK answers here:

http://www.300blktalk.com/forum/index.php

This exact question was asked there recently, and the expert's reply was that 12.5" supersonics would have a velocity about halfway between the 9" and 16" barrel velocities. (Not a big surprise, but these things don't always work the way that intuition suggests.)

I don't know about reliability, which will depend mostly on gas port sizing. If you want to maximize can life I would use a brake-style suppressor adapter (like an AAC Brakeout, or most Surefire adapters) and not worry any further.

 

[rsilvers]

There is no reliability difference.

I don't have 12.5 inch velocities, but the 9 and 16 are on Wikipedia.