Subsonic 300blk. Surprising load data?

[guns4samfie]

I was just going off the Hornady Manual (9th edition) that calls for 2.250". They have 10.4gr of AA1680 going 1000 fps.

If you get good chrono results and are happy with the performance, I wouldn't mess with it!.

With 208's and your barrel (1 in 7 twist?) I don't think you'll have issues with bullet stabilization, but it's not a bad idea to shoot unsuppressed at first, at least to make sure you aren't keyholing. YMMV. I might just be paranoid about baffle strikes....

 

[jpm2953]

Oh ok. My Lee reloading manual doesn't have any 300blk data so I have just been using Google. I will try to go a little longer on my OAL and see what happens

I shot it without the can with 11gr 1680 and it wasn't keyholing. I believe my barrel is a 1:7. Been so long I don't remember.

 

[BillMe45]

As far as I know Hornady 9th is the only in print manual with 300 BLK data.

I'm in for the info. I've never loaded any lighter than 11.5 Gr of IMR 4198 with a 220gr. Off the top of my head they were just a touch under 1000 fps and cycled my 14.5" carbine length gas system unsilenced. I was running a standard buffer and spring. No keyholes through a 14.5" 1in7 AAC barrel.

Most of my work in the past year has been with light weight supers. I've put in a heavy spring and buffer to slow it down a bit I dont know if the subs would still cycle it, havnt tried it.

 

[sold7]

http://blog.silencershop.com/208gr-300-blk-load/

data on the load most use with Amax and AA1650


other good link

http://www.300blktalk.com/forum/viewtopic.php?f=141&t=68693

 

[kwheels]

That data seems about right. I load palmetto projectiles 203gr which typically use about the same charge as the 208gr a-max. I run them over 10gr of 4227, which is .3gr lower than palmetto projectiles listed charge. They list 1680 as 10.2, so I think your data is about right

as for smooth cycling... I recently got a 165gr to cycle reliably subsonic... something around 7gr of reloader #7

 

[SlimChance]

Accurate Arms, Nosler and the Hodgdon reloading guide have data in print