Those of you that get the American Rifleman magazine have most likely noticed the article on the SA Socom II. What I zeroed in on was the velocities since I haven't had the time to chrono my Socom 16. There was also a Dope Bag article on the Panther arms AP4 - 308 which also has a 16" barrel. The velocities are as follows:
SA SOCOM II
Federal 150 Gr. Nosler Ballistic Tip 2583 Avg. Standard Deviation 14
Remington 150 Gr. SP 2474 Avg. Standard Deviation 31
Winchester 150 Gr. Ballistic Silvertip 2517 Avg. Standard Deviation 32
DPMS/Panther Arms AP4-308
Federal Gold Medal 168 Gr. Match King 2479 Avg. Standard Deviation 19
Hornady 168 Gr. AMAX Match 2500 Avg. Standard Deviation 12
Black Hills 168 Gr. BTHP 2457 Avg. Standard Deviation 26
The average extreme spread on groups (@ 100 yards) was 1.01" for the DPMS and 2.75" for the SOCOM II. The DPMS was scoped and since it wasn't specified I assume the SOCOM II was iron sights.
It doesn't appear that the 16" barrels suffer a significant (IMHO) loss of velocity.
Don't most of those 150 gr loads do around 2700 out of 22" barrels? I think 200 fps is significant.
I suppose it depends upon one's ballistical requirements. It averages to a loss of 33.3 fps per inch of barrel (from 22" barrel to 16" barrel). I read somewhere that the loss in velocity per inch would be greater. Maybe I should have stated that the velocity loss is not as bad (or significant) as some of the estimates I have read. I suppose 200 fps could be significant for trajectory and bullet drop, especially at 300 yards or better. At any rate it was the first published chrono data I'd seen and it didn't look to be as bad as some of the estimates I had read somewhere. I should have been more clear.