So much for the reloading manuals and web sites! 5 shots, 2960 average speed, 24 (23.5) in barrel.
I'm hoping to borrow a friend's shorter barrel 308 and see what his rifle gets: I have a 243 and shot it against a shorter barrel - mine's 21; her's is 18.5. Her's shot faster! Not alot, maybe 50-60 fps IIRC.