Aero has a new 12.5 mid length barrel and so far I’m impressed with it. Seems they did their homework on the gas port.



Just be forewarned there isn’t a ton of 12.5” barrels on the market but I had a 12.5” bcm carbine barrel and it was punchy and gassy as fuck with every combo of buffer. It’s kind of just a less developed space.

Green Mountain bbl blank

White Oak bbl extension & bolt

Send all 3 to Paladin Machine of South Carolina w/ your specs, including gas port diameter & location.

I'm on the 12.5" train. My first SBR back in 2011 was an 11.5" BCM. It was awesome and I liked it well enough. However, I don't have it anymore. Then I built a 10.3" gun and it is nice and compact. I was shocked how much different it felt from the 11.5", but that could have also been that it was lighter. That is my wife's HD gun and a Turbo T2 resides on it. I replaced my 11.5" with a 7.5" 300 blk. My next go to was a P&W 13.7". That was replaced with a 12.5" build. I REALLY like that length. The data really does show that it is the best all around length, IMO. With a Turbo K on the end, it is only an inch or so longer than the 10.3" with T2, but much higher velocities.

https://www.youtube.com/watch?v=9q03ZkC4VUs

Basically it boils down to what speed you can get your 55/62 grain fmj too frag.  You want 2500 or higher.  Start going below that then tumbling is the goal with 75/69 grain.  There is a thread in gd about this topic.  Also numbers off the top of my head.  11.5 for me.  10.3 started to get below target numbers in my head.