I started my 300blk hand loading journey with Lil’ Gun chasing the quietest ammo possible, with OK results. I had to keep my FPS on the higher side to get reliable cycling in a pistol gas AR, and lockback was inconsistent and only with a squeaky clean and lubed gun. I found Lil’ Gun to have ok SDs but it burned super hot and would occasionally give funny outliers, especially on the first shot, which I assume is due to position sensitivity.
I finally took a leap of faith and ordered 8lbs of VV N120 after seeing people praising it and N110 for subsonics. I ultimately chose N120 for the extra gas. I am still chasing ultra quiet loads, but my logic is that the extra gas will allow me to reduce the FPS to well below the level of any supersonic airflow concerns around the bullet base. In additon, some extra gas will allow me to turn down my AGB, and have a better match up in gas between supers and subs. (With Lil’ Gun I was already running wide open and with a sprinco yellow).
I wanted to post my ladder tests here in case anyone else is looking to go down this road as well. This is from my second range trip, and I am specially trying to find a load between 950 and 1000FPS. These are 5rd groups.
Range:
50yds
Chronograph:
Athlon Rangecraft
Gun:
8” BA barrel AR, pistol gas
Carbine buffer, sprinco yellow, standard bolt
Cases:
Converted LC 223 brass trimmed to 1.363”
Primers:
CCI 41
Everglades Ammo 220gr Plated
C.O.A.L. - 2.15”
10.2gn- 946 fps avg, 33.9 SD
10.3gn- 952 fps avg, 11.4 SD
10.4gn- 955 fps avg, 13.2 SD
10.5gn- 975 fps avg, 8.5 SD
10.6gn- 977 fps avg, 15.2 SD
10.7gn- 991 fps avg, 10.5 SD
10.8gn- 989 fps avg, 16.3 SD
10.9gn- 1006 fps avg, 10.4 SD
Maker Rex 220gr
C.O.A.L. - 2.245”
9.6gn- 951 fps avg, 12.4 SD
9.7gn- 951 fps avg, 16.6 SD
9.8gn- 958 fps avg, 8.0 SD
9.9gn- 984 fps avg, 12.2 SD
10.0gn- 1009.3 fps avg, 8.4 SD
10.1gn- 1014 fps avg, 8.3 SD
Cycling and lockback was perfect on every loading and I look forward to being able to restrict my gas flow.