Subsonic 300 Blackout using Lapua 200gr FMJ bullet and new Jagemann brass with the Ammo Inc stamp. This load is optimized for 16" rifles but achieves decent velocities from SBRs. We've tested this ammunition to validate the factory claims (which is 1,090fps from a 16" bbl). They're right on. Long-barrel shooters will find this to be very consistent ammunition.
MOQ is 200rds (10 boxes).
16" PSA Upper (Konuspro M-30 set to 2x magnification)
Average velocity for our 20-round string is 1,088 FPS. Standard deviation is 11 fps with an extreme spread of 50 fps (1,068 fps - 1,118 fps). We didn't shoot paper for groups but we effortlessly hit a 6" hanging steel target over and over again at 200yds. We used a Magnetospeed chrono for all measurements.
8" SBR Upper
We shot for chrono numbers from an unsuppressed 8" upper. Our chrono gave us an average a little north of 1,000 fps with a standard deviation of 75 fps. Cycling was not a problem. This makes for a very good subsonic plinking round from an SBR. The SBR loading
delivers better performance for SBR shooters looking for a precision round.