375 ultra mag

Mine is a standard freebore but I might throat it out 180-200 thou. I've been really happy with the velocity I'm getting with N570 but it's a super dirty powder and the loads are very compacted, so I might switch to N565/H1000/Retumbo…Retumbo I think would be perfect in this application since it has a similar burn rate to N570 but the same size kernel as H1000…There was a run of it the other day online but for the life of me I wasn't able to buy any. With N565 there's no compaction and w/ 98gr I can get 2730 but it's an absolute max load. 97gr is 2700fps and is better pressure wise. ES of both charge weights has been almost unbelievable at 2-3fps and preliminarily it seems really accurate. It also burns much cleaner and cleans up easier.

If I throat my barrel out to seat the 390gr out to where the boat tail junction is just above the neck shoulder junction I will probably be able to reduce pressure quite a bit, stuff a couple more grains of N565 in there, and get some more velocity…at least that's my hope cause 2850fps with the 390gr is pretty dang sweet.

H4350/RL16/SW Long/H4831sc might also work pretty well being able to seat the bullet out a lot further for the same reasons mentioned above. RL16 was a little slower than N565 during initial testing so I haven't really pursued it considering mine is a single shot on a short action and I'm seeking absolute maximum single shot performance. However from a hunting perspective, using powders w/ the H4350/4831 burn rate you can get a max charge in there and still load it to mag length, which is great! Even if you only have a MV of 2450fps, w/ the 390gr it will still be going 1600fps at 1000 yards w/ 2200ft/lbs of energy. If it expands like I hope, that would be perfect. At that velocity, recoil will be mild, and can be done in a much, much shorter barrel. Like I mentioned before, because of that I'm seriously considering building a rifle for that very purpose. To me a short, suppressed, 375 RUM would just be freaking awesome. I want to see what the on game performance with the 390gr is though before I fully go that route.
 
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I been reading through this entire post. Does the 300 Rum case and the 375 Rum case have a big difference in water capacity? I believe the 338 Rum is slightly shorter and has a slightly reduced case capacity and that is why most have went to the 338 Edge. I wonder how fast a 300 Rum could push a 245EOL Berger if it's correctly throated for it.
 
I been reading through this entire post. Does the 300 Rum case and the 375 Rum case have a big difference in water capacity? I believe the 338 Rum is slightly shorter and has a slightly reduced case capacity and that is why most have went to the 338 Edge. I wonder how fast a 300 Rum could push a 245EOL Berger if it's correctly throated for it.
???
This is a 375 RUM thread…
Not a 300 RUM thread
 
I know but reading all this is making me think about my own 300 RUM. I just figured some of the people may have started with the 300 RUM before going to the next caliber size or 2. Mine is about half way on barrel life and man what some are showing in velocity a 375 is really starting to look really good for the next re-barrel and all the action work. Even with all that energy of those heavy bullets will they even expand at the low velocity of like 1300 fps on game?
 
I'm headed out to Montana on April 17th. To help build my Daughter and Son in laws place . I'm going out Spring Bear hunting with a buddy and I will take his 375 Rum for a Spin ! Excited to connect with a Bear and the 329 gr Hammers!
Should be a great time !

Rum Man
 
Reason I ask is I found a decent supply of 24N41 and thought I would grab it if anyone imagined it would be viable. Supposed to be slower than N570 but a bit faster than H50BMG.
 
OK, I've had great luck with the Speer 270's in my 375 RUM
But... the lead in the nose is so soft, that it easier disforms while in the mag, or even being bumped...
Yes, I've tried some Barnes 375 bullets, but they don't shoot as well as the Speer 270's

Are there any tricks out there, such as a coating over the lead tip, to prevent the lead tip from distorting so easily?
That does NOT effect accuracy

Thanks
 
OK, I've had great luck with the Speer 270's in my 375 RUM
But... the lead in the nose is so soft, that it easier disforms while in the mag, or even being bumped...
Yes, I've tried some Barnes 375 bullets, but they don't shoot as well as the Speer 270's

Are there any tricks out there, such as a coating over the lead tip, to prevent the lead tip from distorting so easily?
That does NOT effect accuracy

Thanks
IF/when you can find them the Accubonds in .375 are great.
 
Took Rifle and barrel to the smith the other day.
I went the whole way, custom reamer from JGS went down to .006 TPI and pushed the shoulder ahead .050" and 40*. Throat for 390 a-tips.
Whidden built me a set of dies off the reamer print.

Does anyone have a mild load for 350 SMK and 390 A-tips using N570 that I can use for fire forming?
I am hoping the SMK will be able to reach the lands to jam for fire forming, if not I'll use the A-tips.

I have a few different solids to test out also once the fire forming is done
 
Took Rifle and barrel to the smith the other day.
I went the whole way, custom reamer from JGS went down to .006 TPI and pushed the shoulder ahead .050" and 40*. Throat for 390 a-tips.
Whidden built me a set of dies off the reamer print.

Does anyone have a mild load for 350 SMK and 390 A-tips using N570 that I can use for fire forming?
I am hoping the SMK will be able to reach the lands to jam for fire forming, if not I'll use the A-tips.

I have a few different solids to test out also once the fire forming is done
Why use good powder for fire forming?
 
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