Kelbly's, BAT, Barnard, Stiller, Surgeon, Savage, Remington, you will see them on on the line in a F-Class match.
Probably more BATs than anything, also Barnards, and Kelbly's...
Stocks, many types. PR&T would probably be the single most common, quite a few Robertsons also, but they are out of business.
Common barrel mfgs are Krieger, Brux, Bartlein, Broughton, Shilen, Rock Creek, Obermeyer.
Trigger are mostly Jewell, some Kelblys.
Scopes, mainly Nightforce, some March, Sightron, and S & B. Very few Leup, they are just not common in the F game.
You're not going to win or lose because you chose a BAT over a Barnard. You're going to lose because the guy beside you reads the wind better, or you're going to win because you read the wind better than he does...