I have a Ruger M77 in 338 Win Mag, and although I haven't used it against the NT buffs I plan to. I have worked up a load for the 300gn Woodleigh RNSN and FMJ. I use 71gn Reloader 22 for 2400fps. It doesn't match the 375 which pushes its 300gn bullet to 2600fps, and can use a 350gn bullet, but If it is your main rifle which you will occasionally use on Buff and mainly use on pigs, then it will do the job. I am going to do a bit more load development work, as I am sure I can get it up to 2500fps, and I want to try AR2213 and AR2217 as well. With proper bullet selection even the 300 magnums will kill buffs. However, none of these are really charge stoppers (even the 375) because they simply dont have the bullet frontal area or weight. For a charge stopper you really need to go up to 458cal & 500gn at 2300fps or more, but the Woodleigh 300gn FMJ in 338 cal certainly shows good penetration (tested on trees), and if you load a couple of them in the bottom of your magazine (and you can shoot straight) you will reach the brain or spine, and even a 7mm in the brain or spine will stop anything. For pigs I have had great success with the Hornady 225gn bullets (either spire point or SST, I haven't tried the interbond yet), and you can push them to 2800fps with 71gn of AR2209. Be sure to work up to those loads from at least 5gn below to make sure they are safe in your rifle.