Gmoney0425 said:
The application would be F- Class
The 'business class' answer to the question about 260 Rem in F-class would be: outlook poor.
Application is everything. XTR explained the rules of F-class, but I'm not sure if it hit home with someone not versed in ballistics. Basically, with a 260, you'd be outgunned by everyone else shooting F-Open; the class you'd be in with 260. F-Open basically means anything goes, and 260 is an inferior choice for that class.
However, if you were shooting LR tactical matches where quick follow up shots were vital meaning reliable magazine feeding was important in standard AR (gas operated, semi-auto) rifles was important, then 260 Rem is a viable option as most high performance magnums don't cycle well and achieve precision in gas operated rifles.
Again; application is everything. I'd never build a 260 F-class gun, but I am building a 260 Rem tactical rifle for use in the Precision Rifle Series (PRS) which demands reliable and high performance rifle operation as well as decent ballistics due to the 'tactical/practical' nature of the contest.
You probably didn't realize you were asking a loaded question! But we're here to help inform regardless.
Take care,
-Bryan