I'm up here in Chilliwack BC this weekend for the BCRA International F-Class tournament... 300, 400, 500, & 600m here, next weekend down in Portland OR for the 'second half'... 800/900/1000yds @ Douglas Ridge. There are folks who believe devoutly in the heavy bullets (190-210) from a .308 for F/TR class... a lot of others use 155's running hot-n-fast (~2950fps), just like the Palma/TR shooters have for years.
A .223 Rem pushing a good quality 80gr bullet at about the same velocity can be very competitive at least out to 600m. I've watched a few Canadian shooters running a .223 in Open class (due to gun weight and ammo configuration plus some subtle differences between US NRA and BCRA rules) and they've been doing pretty damn well relative to the straight-up 'F/TR' shooters. I think the key is you need to get the bullet moving 2900fps or faster if you can at all possibly do so. Longer barrels are your friend here, though I don't think you gain much (probably less than 10fps per inch) past 26" or so. Still, it is 'free' speed, such as it is.
Despite the roughly 'equal' ballistics on paper, the .223 does get tossed about a bit when the wind starts playing rough... but then again, so does a .308. It's all a matter of degrees, but it doesn't take much to go from an X to a 9, or a V to a 4, on these targets... just over a 1/4 minute.
FWIW, I'm probably going to get a .223 Rem F/TR gun for the wife and/or step-son to use when I can drag them out to the occasional match... either get the 24" LW barrel up and running on my 10FP, or get another 12 F/TR w/ a 30" tube and see how high I can jack up the speed ;)
Edited to add: A *very* large part of how 'competitive' you may be will have to do with *you* getting out and learning to read the wind. No two ways about it. Right now I'm about three days into a four-day match... and the scores are so damn tight, both between the leaders in the Open class, and between the leaders in F/TR, that missed wind calls are a death sentence. If you flat f-up your wind call, it don't matter what you're shooting. A .223 is attractive for the simple reason that you can shoot the snot out of them for about 1/2-2/3 of what it costs to shoot a .308... more time shooting, more time learning.
Last edited by milanuk; 08-06-2007 at 12:39 AM..