Lil gun subsonic with 225 gr Hrndy BTHP, mixed results

[Ben B.]

8.75 gr of Lil Gun, 225 gr BTHP, 2.110" OAL, doesn't lock open, about 1050 average fps but SDs of 20-30 depending on when tested thru a 10.5" pistol barrel with a .09 gas port and the adjustable gas block fully opened.

The Lil gun loads are MUCH quieter than the 1680 loads. the 1680 loads function fine. I need to try a different powder with more gas.

[Jim Timber]

Have you played with seating depth at all?

[Maryland_Shooter]

8.75 gr of Lil Gun, 225 gr BTHP, 2.110" OAL, doesn't lock open, about 1050 average fps but SDs of 20-30 depending on when tested thru a 10.5" pistol barrel with a .09 gas port and the adjustable gas block fully opened.

The Lil gun loads are MUCH quieter than the 1680 loads. the 1680 loads function fine. I need to try a different powder with more gas.

GI mag or Pmag?

So it did cycle the ammo?

[Ben B.]

Yes, started at 2.190", with several stops before 2.110". I'm assuming smaller OAL means more complete burn and more gas available to work the action.

[Ben B.]

I'm thinking 4277 will be next attempt.

[Ben B.]

8.75 gr of Lil Gun, 225 gr BTHP, 2.110" OAL, doesn't lock open, about 1050 average fps but SDs of 20-30 depending on when tested thru a 10.5" pistol barrel with a .09 gas port and the adjustable gas block fully opened.

The Lil gun loads are MUCH quieter than the 1680 loads. the 1680 loads function fine. I need to try a different powder with more gas.

GI mag or Pmag?

So it did cycle the ammo?

It mostly cycles the ammo 90% or so, and have used GI & PMAG.

[Maryland_Shooter]

300 BLK is really touchy with COAL; I have the last of my Hornady 225 BTHP loaded with 8.5g of Lil'Gun.

I'll run with a GI Mag and report my findings.

[Ben B.]

300 BLK is really touchy with COAL; I have the last of my Hornady 225 BTHP loaded with 8.5g of Lil'Gun.

I'll run with a GI Mag and report my findings.

I decided, "What the hell, I'll load up 10 rds with 8.5 gr Lil Gun at 2.110 OAL and see what happens". They all cycled, and locked the mag back 2/2 times. The 2nd time, the bolt was not fully back, but did lock. No sonic crack.

So 8.75 gr was not locking the bolt on an empty mag, but 8.5 was. Hmm. Don't know what to make of that. I'll load some more at 8.5 gr & chrono.