Let me recommend before trying cast bullets, measure the distance a bullet has to travel before it hits the rifling. I wish I did that with my JM 336. Only after shooting 500 rounds in load development did I find out, the bullet has to traverse a half inch before it touches the rifling! The maximum cartridge OAL is 2.550". Any longer and you can't eject the round, it is too long for the ejection port.
Cast bullets will never shoot well with a half inch jump. My cast bullet loads won't stay on a 8.5 X 11 sheet of paper at 100 yards. Jacketed bullets are the only recourse.
The best ten shot group I got was 2 inches with N135.
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IMR 4064 shot sub 3 MOA, which is good for my rifle.
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My loads are all much more than book, because my chamber was reamed with a bratwurst. It is huge!
IMR 3031 did well, I think it is the all around powder in the 30-30
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My rifle liked AA4064
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My goal with a 170 was 2150 to 2200 fps. Based on testing factory 150 grain, push a 150 to 2250 fps and no more.
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These rifles are as rigid as a trampoline. More or less, they shoot best at factory velocities. In every instance where I pushed the bullet, or had over pressure conditions, the groups were abysmal.After testing a bunch of powders with 170 grain bullets, I came to the conclusion that velocity variations caused huge dispersions on target. The best powders were those with low extreme spreads. IMR 3031 is a good place to start.
If the bullet has to jump a long distance to the lands, just walk away from cast bullets, they will never shoot well. And, the rifle will never be MOA or sub MOA. But so what, the things will take deer out to 200 yards and that is about eight times as far as the typical shot in the woods.