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300 BLK loaded with AA #9, thoughts from the lab...
Using data for .357 SIG
Bullet weight, 145 grains, max pressure, 33,000 PSI, velocity = 1170,
charge weight between 9.4 ~ 10.5
Using data for .357 Magnum
Bullet weight, 150 grains, max pressure, 33,540 PSI, velocity = 1394,
charge weight between 12.6 ~ 14.0
Using data for 10MM
Bullet weight, 155 grains, max pressure, 32,700 PSI, velocity = 1414,
charge weight between 14.3 ~ 15.9
Quote from "300 Blackout talk Forum": "...I tried 16.0 grs and 17 grs
of AA#9 with a 150 gr FMJ. I was using formed brass. I blew two
primers out . The primer pockets were expanded so that a primer
would not even seat anymore. So I pulled the rest of them. I know it
will run with 125 gr bullets as the data was published in the most
recent Guns and Ammo issue. My fault I suppose..."
So, it looks like, to me, that we start with a chronograph, a target
and loads beginning with 14.0 grains of AA#9 and work our way up?
Somewhere between 14.0 ~ 15.8 grains should be the desired end state,
the barrel length (16.5 inches and beefier chamber OD vice a pistol
barrel OD should contain the pressure.
Accurate published max pressure for AA#1680, in an AR (16 inch M4
barrel) at 54,564 PSI for a 150 grain projectile.
I can't seem to find any comparison data on burn rate.
What do you think?
Using data for .357 SIG
Bullet weight, 145 grains, max pressure, 33,000 PSI, velocity = 1170,
charge weight between 9.4 ~ 10.5
Using data for .357 Magnum
Bullet weight, 150 grains, max pressure, 33,540 PSI, velocity = 1394,
charge weight between 12.6 ~ 14.0
Using data for 10MM
Bullet weight, 155 grains, max pressure, 32,700 PSI, velocity = 1414,
charge weight between 14.3 ~ 15.9
Quote from "300 Blackout talk Forum": "...I tried 16.0 grs and 17 grs
of AA#9 with a 150 gr FMJ. I was using formed brass. I blew two
primers out . The primer pockets were expanded so that a primer
would not even seat anymore. So I pulled the rest of them. I know it
will run with 125 gr bullets as the data was published in the most
recent Guns and Ammo issue. My fault I suppose..."
So, it looks like, to me, that we start with a chronograph, a target
and loads beginning with 14.0 grains of AA#9 and work our way up?
Somewhere between 14.0 ~ 15.8 grains should be the desired end state,
the barrel length (16.5 inches and beefier chamber OD vice a pistol
barrel OD should contain the pressure.
Accurate published max pressure for AA#1680, in an AR (16 inch M4
barrel) at 54,564 PSI for a 150 grain projectile.
I can't seem to find any comparison data on burn rate.
What do you think?