F/TR - 308 Win or 223 Rem, weight limit 8.25 kg or roughly 18 lbs 2 oz.
F-Open - under .35 cal, weight limit 10 kg or 22 lbs.
Both weights are as you would lift the gun off the ground - anything that comes with the gun ie bipod, sling, whatever - counts towards that weight. Fat barrel = skinny bipod, at least for F/TR.
Either config would be viable for shoot for fun, especially @ mid range (3/5/600). Might even be competitive (ish), depending on the local crowd and what they're bringing to the line. Do yourself a big favor and get a single shot 'sled'. Matches are single-load only, and faffing about with tossing rounds in on top of an empty mag gets old quick.
Biggest hang-up most people have bringing their 'tacticool' rifles to an F-class match is NRA rules stipulate no muzzle devices. No brakes, no suppressors. Some small club events might look the other way for the sake of another body on the firing line; larger venues not so much. Generally if you can take off the muzzle device and put on a thread protector, you'll be fine. Otherwise maybe they'll have a tactical/field/other class for guns that don't meet the official rules.