Armory Sponsor
Posted: 8/21/2010 4:00:36 PM EDT
|
while awaiting the delivery of my AAC suppressor, i'd like to try my hand at some 308 subsonic loads so if anybody has been there and done that i'd like to hear of your results. My rifle is a 308 Rem with a 16-inch Schneider barrel. i recently picked up a large amount of 220gr Sierra MatchKing bb's so if there is a safe subsonic load that might work, that's what i'm looking for. I've read that Trail Boss pistol powder works well and have also read that using magnum primers along with an enlarged primer hole produces good accuracy. Am planning on calling some of the powder companies next week but thought i'd ping "the hive" first....
TIA |
|
Before you start off, what's the twist rate in your rifle? Lots of 308's are 1/12. You may not stabilize properly with those 220's.
I've been playing with TrailBoss. Ran some 175SMK in my Bushmaster Custom (1/12 twist also) and they were all over the place at 100 yards. Next load will be with 168's to see if I can tighten them up a bit. ETA: I think I'll try the enlarged flash hole also and see what happens 
|
|
my Schneider is a 1x10 twist.
found this which is pretty informative http://members.shaw.ca/cronhelm/DevelopSubsonic.html |
|
The nice thing about Trail Boss is you shouldn't have to worry about SEE. It's a very "fluffy" powder (density is very low). 9 grains probably fills a 308 case about 3x as much as the same charge with TiteGroup. I think the max you can even put in is around 14 grains? Which is another cool thing about Trail Boss, you can never overcharge a round. Great for low recoil loads as well.
|
|
Unless your barrel is a 1 in 8 twist you are probably not going to stabilize sub sonic rounds with 220 SMKs.
Most people with standard twist 308 barrels tend to use round nose/flat base bullets in the 170-180 grain range as they stabilize better than a BTHP. I have been playing with 180 grain Hornady RNFB bullets behind Trailboss and still have yet to have them shoot consistently well but they don't keyhole in my Rem 700. I can shoot sub sonic 240 grain SMKs in my 300 Whisper but it is a 1 in 8. It is one of my favorate rifles right now. Make sure you do alot of research and testing before you see your AAC can fly off the end of your barrel and go further downrange than the bullet. 
Play around with this: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi |
|
I have had the best results with FLAT BASE ROUND NOSE bullets. start off with around 10-10.5grs and a 180gr bullet.
shoot it plenty to check groups before you try it with the can \I have excellent results with 11.1gr of trailboss and a 180grbullet with a AAC Cylone and a 1/10 twist barrel. I have also had very good groups using the same loads with a M1A. |
|
Unless your barrel is a 1 in 8 twist you are probably not going to stabilize sub sonic rounds with 220 SMKs.
Most people with standard twist 308 barrels tend to use round nose/flat base bullets in the 170-180 grain range as they stabilize better than a BTHP. I have been playing with 180 grain Hornady RNFB bullets behind Trailboss and still have yet to have them shoot consistently well but they don't keyhole in my Rem 700. I can shoot sub sonic 240 grain SMKs in my 300 Whisper but it is a 1 in 8. It is one of my favorate rifles right now. Make sure you do alot of research and testing before you see your AAC can fly off the end of your barrel and go further downrange than the bullet. Play around with this: http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi excellent.....thanks for that info ! I've got a good starting point now.... |
|
Quoted:
excellent.....thanks for that info ! I've got a good starting point now.... Your welcome Playing with subsonic 308s out of a bolt gun is fun as hell but be sure not to damage your can by testing. My experience has been what cruizer said, 10, 10.5, and 11 grains of Trailboss with a 180 grain RNFB seem to be subsonic out of my 20". You have a 1 in 10 twist which in my opinion is the best twist for a 308 that you will be shooting both supersonic and subsonic rounds. This is what twist Rem is now using in their rifles specifically geared towards suppressors. http://www.remington.com/products/firearms/centerfire/model-700/model-700-sps-tactical-aac-sd.aspx |
Armory Sponsor