Load for 300 BLK Short Barrel?

[Woolecox]

Looking for a good load for my Sig MCX 300 Black Out. Weapon has a 9" barrel and it is suppressed. The idea is to get 220 gr Sierra MK and Round Nose to run about 1050 fps in this Sig.

Yes, I know there are tons of data out there on the 300 BLK. I have access to it all and most of the common powders used for the 300 BLK. Problem is, it is all for a 16" barrel. Obviously, those load will be much slower in a 9" barrel. I don't want to loose a lot of velocity shooting those loads. I want to keep it just below the speed of sound to retain as much energy as possible.

I will get out later in the week and chronograph some loads but it would be nice to have a starting point.

 

[Texas10mm]

http://www.300blktalk.com/

Do you have a chronograph? If so just start loading. Work up till you hit the velocity you want.

 

[mcb]

In my experience sub-sonic loads don't change that much going from 16-inch down to 9-inch. Supers are much more effected by that change in barrel length than subsonic loads.

I have both a 9-inch and 16 inch 300 BO firearmes. The 16-inch barrel is a Ballistics Avantage and the 9-inch barrel and AAC. I have chrono'ed a few of my sub-sonic reloads in both. Hopefully this will help. Obviously these loads were worked up to, as usual.

My subsonic plinking loads is:
Bullet: Barry's 220 gr spire point plated
Primer: Winchester Small Rifle
OAL 2.190"
Powder: IMR 4227
Charge: 10.1 gr
Average Velocity 16-inch barrel: 1068 fps (5-shot)
Average Velocity 9-inch barrel: 976 fps (5-shots)

My subsonic hunting load:
Bullet: Maker 220 gr REX
Primer: Winchester Small Rifle
OAL 2.150"
Powder: Accurate 1680
Charge: 10.4 gr
Average Velocity 16-inch barrel: 1066 fps (5-shot)
Average Velocity 9-inch barrel: 977 fps (5-shots)

Basically 90 fps lost going from 16-inch to 9-inch. My super sonic loads are closer to 200 fps over the same change.

 

[Lennyjoe]

I use 10.5 gr of 1680 under a 208 gr Hornady BTHP out of my 10” barreled, AAC Cyclone suppressed .300 BO SBR.