I have a 338 Win Mag in a Ruger Mark 11. I had a mussel brake add to the barrel. Didn't change anything except the recoil. I had it done at Accurate Arms in Missoula, MT. I having a rifle in 338 Win Mag coming from him, but I have a 26" barrel instead of a 24" like on my Ruger. With the Ruger I am getting 3220 fps with a 200 gr. Nosler Accubond, and petty much a tack driver. I am not a long range shooter. I stay within 500 yds. My son got a 338 Win Mag in a Browning that the barrel is ported. We run up the powder load, and that checks out. Going see what the chronograph tell us and work COAL too.
SSS
Mike