BLUF / TLDR: do you recommend A1680 or CFE BLK (or something else?) to:
(In order of priority)
- drive a 190 gr subsonic Hornady SUB-X (essential)
- generate enough gas to reliably run a suppressed 8” SBR (also essential)
- be as quiet as possible (desirable)
Long version:
I finally got my suppressor for 300 BLK (SF 762-MINI2), and am testing subsonic ammo.
I’m using an 8” Aero upper.
I can get 220 gr subs to cycle and lock back with the same buffer/spring setup I use for supers. This was a pleasant surprise.
And 200 gr subs will function with lighter buffer/spring.
But my “primary” desired load - Hornady 190 gr SUB-X will cycle, but not consistently lock back with even a light carbine buffer and spring equivalent (I have a LAW folder installed, so reduced the buffer weight to generate the same reciprocating mass as a standard BCG and carbine buffer).
I’m a bit puzzled, as I didn’t expect to be undergassed when suppressed (although Surefire emphasizes their low back pressure).
So, now I can:
1. Lower reciprocating mass by getting a low-mass BCG (can save 3.4-3.7 oz) for $150-250. This is the most expensive solution, but would certainly address the issue. And a titanium BCG would be cool to look at.
2. Lower buffer spring resistance with a weaker spring (already ordered from Sprinco for $30 shipped)
3. Increase gas pressure by loading a “hotter” 190 gr SUB-X load
I’m digging into pursuing the 3rd option. The Hornady factory load is spec’d for 1050 fps out of a 16” barrel. I’m certainly getting a fair bit less than that out of 8”, so I figure if I use Hornady load data spec’d for 1100-1150 from a 16” barrel, I will likely still be subsonic out of 8”. And (most importantly), generate more gas to run the gun. I plan to use an iterative process to avoid the supersonic “crack” while keeping the charge as high a possible for gas to run the gun.
I’m going to order the Hornady projectiles tonight.
Will A1680 or CFE BLK best meet my needs?
@Trigger