First off I want to say I am a veteran loader but have just tried to get serious since last year. I have a .338-.378 weatherby mag that is giving me nothing but grief lately. It shot not bad groups at 100 yards (1/2" to 3/4") with a 200 grain nosler ballistic tip. I was using IMR 7828 powder. I want to use a slower burning powder and larger bullets but am having no luck. I want to try 250 grain bullets and a slower powder. I have tried retumbo, us869, h1000 and assorted bullets sierra, lapua, barnes, berger but have moved up to 3" groups with these. Any suggestions other than the little bullets and finicky powder? rifle is a 1 in 10 twist the same as a friend's trg 42 which loves the 250's.
.338-.378 dilema
- Thread starter Lee Verge
- Start date
RL25, H870/8700, work pretty well. You may want to try a few different heavy bullets as well. - dan
Does your rifle still shoot 1/2 to 3/4 " groups with your 200gr Nosler B/Tip load? Going from 1/2" groups with hunting bullets to 3" groups with target bullets tells me the problem is not with bullets or powder. Check everything on your rifle - action and barrel bedding, action screws, rings, bases, barrel crown and if all that fails try another scope. You must eliminate all of these possibilities before you resume load testing. Go back to the best load your rifle liked in the beginning and use it as a base to see if your mechanical corrections have found the problem.
Regards; Aubrey
Regards; Aubrey
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Good call guys. I havent tried those lighter bullet loads in a while. I'll go back to the drawing board with what worked and make sure it still is...... never thought of that.... my buddy was telling me to try some bigger bullets slower with less pressures and see what happens as well. Might have the cannon looked at first..
Hello Lee
I have a 378 Weatherby mag that gave me a lot of grief for years to get to shoot. I was getting 12 inch groups or more at 100 and had everything on the gun looked at, sent the scope back to the factory 3 times, they sent it back saying it was ok. Found the problem WAS the scope. Bought a Swarovski and problem was over. These guns kick hard and are scope killers. Once I got the eratic group problem solved, I use RL22 behind a 270gr TSX and shoots 1/2 to 3/4 inches at 100 yds for 5 shots, BUT I must let barrel cool between shots and keep the barrel clean. My barrel copper fouls bad and if I shoot to fast and don't let the barrel cool between shots, the groups open up to around the 2 to 3 inch mark. My rifle is a MK V deluxe weatherby and I had the barrel bore scoped and it has a lot of tooling marks in the barrel from factory, which is no doubt the cause of the excessive copper fouling. I have since ordered a Krieger barrel to replace it with. Just waiting for it to show up.
In short, keep your barrel clean, cool, and use a high quality scope and ring set with these harsh recoiling rounds.
I tried 4 or 5 powders and RL22 gave me the best group and second highest velocity in my rifle.
I have a 378 Weatherby mag that gave me a lot of grief for years to get to shoot. I was getting 12 inch groups or more at 100 and had everything on the gun looked at, sent the scope back to the factory 3 times, they sent it back saying it was ok. Found the problem WAS the scope. Bought a Swarovski and problem was over. These guns kick hard and are scope killers. Once I got the eratic group problem solved, I use RL22 behind a 270gr TSX and shoots 1/2 to 3/4 inches at 100 yds for 5 shots, BUT I must let barrel cool between shots and keep the barrel clean. My barrel copper fouls bad and if I shoot to fast and don't let the barrel cool between shots, the groups open up to around the 2 to 3 inch mark. My rifle is a MK V deluxe weatherby and I had the barrel bore scoped and it has a lot of tooling marks in the barrel from factory, which is no doubt the cause of the excessive copper fouling. I have since ordered a Krieger barrel to replace it with. Just waiting for it to show up.
In short, keep your barrel clean, cool, and use a high quality scope and ring set with these harsh recoiling rounds.
I tried 4 or 5 powders and RL22 gave me the best group and second highest velocity in my rifle.
