Subsonic 300blk. Surprising load data?

[jpm2953]

so, I recently got my SBR and Suppressor stamp and I have been working on a Load for it. Subsonic. I am using 208gr A-max, 1680 powder and CCI 450 primers

I have loaded down to 10.3gr at a OAL of 2.200". This seems to be much lower than other data I have seen. Other folks are from 10.6 to 11.0gr of 1680. I must have the best cycling 300 blk out there. So I guess my question is, anyone else loading that low? It cycles and holds the bolt open on the last round.

Spikes upper and lower with a Cmmg 8.5" barrel. Pistol length gas system. AAC 7.62 SD can.

 

[WC1911guy]

In for this info.

 

[guns4samfie]

Have you gotten it on a chronograph by chance? Does it cycle without the suppressor?

Maybe the 450's and relatively short OAL are giving you a little extra pressure.

 

[DinkyDau]

What buffer piston are you using?

 

[JDG.]

Yeah, Id like to know the fps as well. I use the 208's but for a bolt gun

 

[ltfirhunter]

986 fps thru my bolt gun, with suppressor, 9.2 gr AA1680
992 fps. with 8.8 of H110

with a 208 Amax

 

[ocean_glocker]

In for data

 

[jpm2953]

What buffer piston are you using?

It's a spikes ST1. Standard carbine buffer.

 

[jpm2953]

Have you gotten it on a chronograph by chance? Does it cycle without the suppressor?

Maybe the 450's and relatively short OAL are giving you a little extra pressure.

Haven't tried without the suppressor since I won't be shooting it without it. 2.200" is short? I have seen several loads shorter than that. I will try with some CCI 400's as well.

It's ejecting the brass a good 6 feet so it's not like it's barely cycling.

 

[jpm2953]

And haven't Chrono'd yet. Hopefully soon