Ammo blowing apart at muzzle

[ptbobdemaria]

I have put maybe 100 rounds through a custom build Bear hunter in 300wm with no proble. I was having trouble with scope, put on new rings and took her to range. I put a few factors hornady american whitetail 150gr rounds through it and after thinking I wasn't on paper, I realized the bullets are blowing up at the muzzle throwing shrapnel down range. It does have a muzzle adjustable muzzle break on it. Break was on. Any clue guys?

[m12lrs]

Two thoughts

They could.be striking your muzzle device. If you can remove it do so and see if you can see any damage. Otherwise it is a flashlight from the.muzzle.

Another problem is 150's are mighty light for.a win mag. You might be driving them at a velocity where they self destruct.

[darkker]

You are on the right path, just need to clean-up your terms. RPM is what may be destroying them, not velocity.

Agreed, check the brake for contact. But likely those very light bullets can't stay together.

MV * 720 ÷ twist = RPM
If your are about 290,000 or above, it's the RPM.

[Robinhood]

Factory ammo fellas. Unless by custom he means 8twist, I don't think Hornady would be that far off.

[ptbobdemaria]

Yes, factory ammo. And I didnt change the barrel, still the original 1:10 twist

[darkker]

Then your brake has an issue, or you have a 1980's Savage bore.

[ptbobdemaria]

I was thinking maybe the muzzle break had something to with blowing apart light bullets.... and if so, maybe that's why I'm having accuracy issues with 180 bullets and it's not my scope. Which I've been trying to determine....

[Front Royalty]

Process of elimination. Remove muzzle brake.

Does problem persist?

No: you have a brake contact issue.

Yes: You need to dig deeper into RPM as mentioned by other posters.