Does anyone have load data for .308 subsonic rounds. A friend has a Rem. 700 equipped with an AWC Thundertrap suppressor that is just wicked with SS ammo.

I am sure you will not find any SS rounds. Your slowest velocity rounds would be of the cast lead variety. I have gone back to 1953 reloading books and the slowest bullet loads i found were 1355 fps. Sorry. vangunsmith

check out Trailboss powder
your going to have to start super sonic (13 grains over magnum primer w/ 150 grn bullet)
and work until it drops under the speed of sound

here's a good page to start with...

http://members.shaw.ca/cronhelm/DevelopSubsonic.html

group over here have been discussing it.

http://www.silencertalk.com/forum/viewtopic.php?t=7235

I'm just starting on it now.

IMR 4759 and the bullets you want to use, should be among the most accurate and quiet.

1725fps is the slowest I got with a 150rn out of my CZ550. Used 12gr Somchem MP200 with a cotton wad. Accurate as hell too!!! I think Lapua loads an SS round......