Wow, that 500-bullet box is HUGE (Sierra 240 HPBTs)

[WhisperFan]

Originally Posted by RWBlue

No problem, but please post your info as you develop it. We are all learning from each other.

I read somwhere that 9.9 of AA #9 was a subsonic load for 220 SMK's

I loaded up about 8 to try and they were subsonic out of my 10.5" 1-in-8 pistol barrel, but they broke the sound barrier in my 18" 1-in-7 twist PacNor barreled Remington 700.

I guess the longer barrel allowed for a longer burn time and a faster muzzle velocity.

I have an 8# keg of AA#9, so I am pretty much married to that - any suggstions as to a load that will be subsonic in both rifles?

[320pf]

Whispefan,

The Accurate reloading manual lists 8.2 grains of AA#9 pushing a Sierra 220 HPBT out of a 16" barrel at 1056 fps. So I suggest that you back-off the 9.9 load until you just go subsonic in you 18" barrel and then you should get the results that you are looking for.

http://www.accuratepowder.com/data/P...0page%2076.pdf

I have tried both the 165 and 190-180 (with 180 Sierra GK) loads using AA#9 and have been able to reproduce the loads found the loads listed in the Accurate manual.

Here is one that works very well in my 16" AR15.

7.5 AA#9 pushing a Sierra 180 HPBT at 1034 fps

http://reloadersnest.com/unverified_...ID=135&ID=3009

So I think that if you try out the loads listed in the Accurate reloading manual you should get the result that you are looking for.

320pf

[AR15barrels]

I happened into an old 500ct box of 250gr Sierra MK's on eBay several years ago and I have been using them sparingly.