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Best copper or bronze mono-metal bullet for expansion?

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Go for it. Will be a learning experience one way or another for sure.
This has me thinking of getting a 1:6" twist barrel for my 300 RUM to try 180gr to 240gr mono's. And, see what it does with 250gr lead. At least 3,200 fps with 250gr would be great to try to get to.

I'm also curious to see how the CEB 240gr Lazer mono performs compared to the Berger 245gr and A-Tip 250gr at 1,000 yards and beyond.
 
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Here's some real world numbers.

IMG_3774.png
 
Twist rate will not affect speed but some will argue that the faster the twist the more resistance driving the bullet forward resulting in a decrease of speed, I've never tested this though. Add 25fps for every inch in barrel length but….. eventually that falls off as well. You will probably/maybe get an extra 50-75fps for the length from 24-28 but who knows. Im out on this one.
 
Based on your original post you should already know what your rifle will do with the heavier cup/core pills. It will not be fast with the same weight mono. What's your recorded speeds with all the testing you mentioned in your OP?

"I recently bought a rifle chambered in 300 RUM, 28" inch barrel, 1:8" twist. Looking to hunt with it and shoot heavier 220gr to 250gr. My experience with the 300 RUM is limited. My shooting so far has been with Hornady ELD-X 220gr, A-Tip 230gr and 250gr, and Berger LR Hybrid and Elite Hunter 245gr."
 
Based on your original post you should already know what your rifle will do with the heavier cup/core pills. It will not be fast with the same weight mono. What's your recorded speeds with all the testing you mentioned in your OP?

"I recently bought a rifle chambered in 300 RUM, 28" inch barrel, 1:8" twist. Looking to hunt with it and shoot heavier 220gr to 250gr. My experience with the 300 RUM is limited. My shooting so far has been with Hornady ELD-X 220gr, A-Tip 230gr and 250gr, and Berger LR Hybrid and Elite Hunter 245gr."
245 Berger
3010 fps
Carbon Six
28" inch barrel
1:8" twist
92.5gr N570
Rem cases (virgin)

995 yards showing 4'' vertical on 3 shot groups .5moa. 92.5gr N570. At around 93gr my groups started opening up.

This was after much testing. I started off with 83gr of N570 looking for pressure signs but, I wasn't happy with the results with velocity.

This is my first 300 RUM. I bought this rifle in early 2024 so I'm still working with it.
 
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245 Berger
3010 fps
Carbon Six
28" inch barrel
1:8" twist
92.5gr N570
Rem cases (virgin)

995 yards showing 4'' vertical on 3 shot groups .5moa. 92.5gr N570

This was after much testing. I started off with 83gr of N570 looking for pressure signs but, I wasn't happy with the results with velocity.

This is my first 300 RUM. I bought this rifle in early 2024 so I'm still working with it.
Perfect…… a mono of the same weight will be MUCH slower!!!! They are longer and you can't get as much powder in the cartridge.
 
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