The fact that you have a long action with magnum bolt face pretty well limits you to what you can use. You could go to a WSM or SAUM, but they may not feed well from a long action magazine. I have had them feed well from a long action magazine by filling the back of the magazine with a .223 block, shortening the follower and using a .308 magazine spring. If you're shooting single shot, then magazine function isn't a problem. The few guys that I've been barreling for F-class have used 6.5-284, .284 and 7 SAUM on the last one I barreled for them. Barrel life was an issue with the 6.5-284. The .284 worked well, but they went to the 7 SAUM to gain more velocity than what the .284 would get. I haven't heard back from them on the SAUM. What I'd suggest, is if you've been doing well shooting the .300 Win Mag in F-class, then stick with it. If you have been finishing middle of the pack, then I'd look at what the ones who have been winning have been using. It all just depends upon what your goals are in what event you are competing. For a .300 Win Mag, I probably wouldn't go with a 22" barrel as you'd be having too much powder falling out the end of your barrel unburned and be loosing velocity. You can check for unburned powder by putting a white sheet on the ground, shoot your rifle off a bench and see how much unburned powder is on the sheet after you shoot. I'd suggest at least 26" with a .300 Win Mag. Cut it at 22" and you'll lose velocity. How much, I don't know but it's normally 25 to 50 fps per inch cut off depending upon caliber. I don't shoot F-class, but I have built rifles for guys shooting F-class. Also, as to the 22" barrel length, it may work better for your tactical matches than a 26" barrel. It just depends upon how the matches are set up and what kind of competition it is. That's the bad thing about using the same rifle in two different types of competition. It usually winds up being a compromise rifle for one or the other event.
