Two of my 338 win mag shot 4 inch groups at 100 yards with the nosler 225 grain Accubonds .My stainless ruger 77 338 win mag shot 225 speer grand slams into a 3/4 inch group at 200 yards but they quit making that bullet .It seems to shoot traditional flat base bullets best .I will have to have a muzzke break if I go above 225 grains .I have a 338-378 weatherby just didnt want to use it on deer unless I have to .I can handle up to 275 grain bullets with the 338-378 with the muzzle brake on it .
Sierra makes a 215 and a 225gr hunting bullet I would not consider them long range but would work fine under 500 I believe the 225 is a flat base might solve your problemTwo of my 338 win mag shot 4 inch groups at 100 yards with the nosler 225 grain Accubonds .My stainless ruger 77 338 win mag shot 225 speer grand slams into a 3/4 inch group at 200 yards but they quit making that bullet .It seems to shoot traditional flat base bullets best .I will have to have a muzzke break if I go above 225 grains .I have a 338-378 weatherby just didnt want to use it on deer unless I have to .I can handle up to 275 grain bullets with the 338-378 with the muzzle brake on it .