150 Grain Subsonic Questions

[db300]

Seekins Precision 8" 1:7 Omega, LMT full auto BCG w/ standard carbine buffer and spring. Adjustable block. Pistol gas tube.
GDY WIN 147gr FMJ MII
Mixed head stamp, once or twice fired from Freedom Munitions originally
CCI 450
A1680 (progressive grains, see below data)
COAL 2.138-2.142

After watching the posted YouTube videos above, re: positional change and varying velocities, i decided to shake the gun in a horizontal position downrange up and down a few time before each fire. Hopefully this oriented the powder similar each time but who knows. Not exactly scientific.

10.8 gr 1094, 996, 968, 959 fps
10.9 gr 990, 1183, 1163, 1217 fps
11.0 gr 896, 972, 890, 876 fps
11.1 gr 900, 1184, 1206 fps
11.2 gr 938, 1177, 1252, 1221 fps
Caldwell chrono @10 ft. 1122 ft, 34%, 29 inHg, 61F
All loads cycled and held held the bolt open. All fairly inaccurate.

I see now why no one shoots lightweight subsonic suppressed. I appreciate the advice from above members. I'm new to reloading but have an excellent mentor. I look forward to sharing some future data.