You have two classes in FClass comps. Both shoot together but compete in own class.
1. Open- any caliber and this is the hot rod class. this is where the 6.5-284, 6 BR derivatives, 284 etc compete. Can shoot off front rests too.
2. FTR (target rifle) and limited to the 308 and 223 calibers. Take a 308 with Palma #1 reamer from Dave Kiff, 30-32" standard or light Palma contour in 13 twist with the Berger 155.5 bullets and you are good to go. Super barrel life and you only compete against 308s (primarily) and 223s (require 1-9 twist and 90 gr bullets for 1k). Only bipods are allowed, no front rests.
F-Open shooters consider barrels a consumable, just like brass and bullets. To be really competitive you need a ultra high performance round like the 6.5-284 or a real fast 7mm.
What I am researching a lot lately is the 6CM (CompetitionMatch) it's a 6mm made for launching 115dtacs and other heavy 6mm bullets. It uses slow and cool burning single based powder (H1000) to extend barrel life. 115dtacs at 3100+ with around 3000rounds of barrel life. Reseach it a bit, and take it with a grain of salt, I haven't fired one or seen one in action, but heard some several reputable guys about it. They also used some VV powders and pushes the dtacs to 3300fps, but that drastically reduces barrel life.
I started a thread titled "big 6mm's" might want to search it.
Another opion would be to get a 308 with a long barrel and just go the cheap way out. Still shooting f-class, but not going though at least one barrel a season.
From your experience I would suggest you build a nice 308 with a match chamber and shoot the FTR instead of the open class. Save up your money and get a nice front rest and good br stock and build up a 6.5x284, 6x47L, or possible a 7mm. Get your experience in these type of comps and then move to the open class when your ready. Take care.
Hmmm... I don't think I ever saw an answer to what distance you intend to shoot primarily. It does make a difference, in my opinion.
If'n it were me... I'd say if the *majority* of your shooting is going to be @ 600yds and in (i.e. you might only get to a true LR - 800-1000yd - match once or twice a year), get a 6 BR, Dasher, BRX or something similar. The wind advantage of the big heavy bullets isn't going to outweigh the lower recoil, lower cost, longer barrel life, and sheer accuracy of the small-to-mid sixes.
If you are located where you could conceivably expect a reasonable split between your mid-range and long-range shooting... I'd say one of the mid-sixes (6 Dasher, 6x47, 6CM, etc.) or one of the mid to large 6.5mm (6.5x47, 6.5-08, 6.5x55, 6.5-284) calibers. As Kevin Thomas pointed out, the 6.5-284 has an excellent reputation for LR accuracy; the US F-Open team didn't pick it by accident. It is a bit of a waste, in my opinion, at the mid-range distances. More than a few shooters won't pull a 6.5-284 out of the case until the range goes *over* 600yds, as barrel life tends to be short enough and the ballistic advantage small enough that it just isn't worth it. Its not that a 6.5-284 isn't accurate enough to win at the closer distances, but it's not really being used to its full effect.
Finally, if you live near an active 1000yd range... it might be very much worth going with a bigger caliber. They do get more difficult to shoot as accurately, and depending on how you go about it, they can get dang expensive to shoot as well. Some of the combinations that are in use such as 7WSMs and 7RSAUMs that are loaded *very* hot (B180VLD over 3100fps) have barrel life (500-700rds) that makes a 6.5-284 look good. One of the guys I watched @ the 2009 FCNC was punting B210VLDs out of a .300WSM... dunno what the velocity was, but he was actually using a vertical grip on the fore end to control the jump & torque. Not my taste, but its an option. Of these bigger calibers, the .284 Win and .284 Shehane (improved) seem to be gaining interest - Charles Ballard has won two years in a row with his as well as setting the standing record @ 1k. The same B180VLD @ 2800-2900fps with markedly better barrel life and less recoil, plus Lapua brass (6.5-284 necked up, oh the irony ) to boot. Charles also lives fairly close to the NSSC 1000yd range @ Camp Butner in NC - so he can spend as much time as he wants at the 1k line. Somehow I doubt he'd field the same rig if the majority of his matches were 600yd and in.
Someone mentioned going .308 instead... and I do think that might be a viable option. If the rifle is a Savage (thought I saw it mentioned as a 110 somewhere in the tread), then barrel changing is extremely easy, and you probably already have a .473 bolt face... so changing the barrel to a 30" .308 medium or fluted heavy Palma contour with a twist between 1-10 (for 210gr bullets on down) to 1-12 (probably 185gr bullets on down) would be no problem at all. The barrels last a bit longer than most of the options mentioned above, less crap to carry around (no front rest, etc.) and pretty simple to get up and running. The F/TR class is less about equipment and more about who reads the wind better - and anyone can learn.
If you want to win much in F Open, it's going to take a 6.5-284 or 7mm of some type, though you might pull it off with Dasher or 6mm derivative if you shoot where the wind doesn't blow much.
If you want to learn, and learn wind calls, you can do it much cheaper with a .308 and shoot in FT/R.
It's much cheaper to shoot, there is lots of match quality ammo available, as well as match brass. You can jump in easy with a Savage factory rifle, and they shoot well enough that the US F class team was mostly the Savage factory shooters! A decent .308 barrel will probably go 3-5000 rounds, easily 3 times what the 7mm and 6.5-284's will do.
I'm addicted, and I don't find that shooting 60-100 rounds of 7mm WSM causes me any problems on day two of shooting, but some people do evidently. If you shoot a rifle in the higher legal weights, it just doesn't seem to be much problem. Shoot an 8 pounder for 60 shots, I bet it would beat you up. Shoot an 18 pounder, not so much.
Of course, I'm just a shooter, not a national level guy, so take anything I say with a grain of salt!!
I thought someone like you might know this.... but a light bullet recoils less... a heavy bullet recoils more.....
Guns I own: 300 winchester magnum, 7mm Rem mag, 243, H&R 22 revolver, BT99 12 gauge, 20 gauge break action. 20 gauge pump, 22 break action, 257 Roberts, winchester super x 1. Wishlist: 308 winchester, 6.5mm-284 Norma, 17 HMR, 7mm RUM, another 7mm rem mag LOL, 44 magnum revolver, 30-30 lever action, 44 lever action.