375 RUM Build

Doublezranch

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Mar 24, 2011
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North Dakota
+P = By having a step in the lands, the bullet is farther down the bore before it hits peak pressure from the lands which effectively increases case capacity. How much will your case capacity increase?
 

Whitetail312

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Jun 15, 2018
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Loganville, GA
+P = By having a step in the lands, the bullet is farther down the bore before it hits peak pressure from the lands which effectively increases case capacity. How much will your case capacity increase?
I’m not 100% sure as of yet, I would assume 5-6 grains but I could be totally off.
 

Doublezranch

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Mar 24, 2011
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The reason I ask is because we tried the 329’s in the 375 Zayne. It’s usable case capacity with the 329’s was 125 grains.

I am rebarreling my 375 rum and will be adding a 28” barrel on it. I’m after the 300 grain bullets.

What twist did you go with?
 

Whitetail312

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Jun 15, 2018
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Loganville, GA
The reason I ask is because we tried the 329’s in the 375 Zayne. It’s usable case capacity with the 329’s was 125 grains.

I am rebarreling my 375 rum and will be adding a 28” barrel on it. I’m after the 300 grain bullets.

What twist did you go with?
I went with a 1:8:5 twist.

I’ll do my best to configure the useable case capacity now
 

jw375

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Sep 23, 2015
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Oregon
Finding peak pressure for the 375 RUM +P is going to have everything to do with which bullet you decide to go with. In my 375 RUM+P I found the 350gr SMK to hit that mark faster than the 329 Hammers. My opinion and in speaking directly to Sierra about this subject, that has to do with the jacket of the SMK and how it interacts with the rifling. There a ton of torque there. The hammers are definitely less. Some of that having to do with the bullet weighing less, but most I believe is in the design of the bullet. The Hammer, even though it’s not as slippery, can just be pushed harder and faster. Thst will make up for some of the BC loss. That being said, I have shot 101gr of Retumbo behind a 350 SMK and didn’t see any ejector marks. Still hard on the brass though. Myself, I don’t like pushing my brass hard. It’s part of the reason I’m ok with buying more expensive hammer bullets.
 

robert l

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Feb 28, 2016
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422
Location
manatee county florida
What round and COAL do you shoot?
It will feed 3.95 inch And i have had no problems with recoil banging the the bullet back into the case.i may be just lucky because the people that i know that shoot with the same box have problems with that length.I do use a little bit more neck tension than they do.So that could be why it works for me.
 

apercep

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Jun 22, 2012
Messages
13
Hey guys, here to chime in with my build. It’s a old Weatherby vanguard action that was sent to Pac-nor for a rebarrel. It’s a 30” straight taper 1”muzzle 1:10twist. In a MDT HS3 chassis. It was chambered and throated around the 330gr Lehigh match solid at 4.200”. I have not started load development yet. I have run some factory ammo through it. The 270lrx Barnes is coming out at 3014 and prints 1/3moa. Took a moose last fall with it at 397yds. Can’t wait to start working up loads for it!
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David Emerson

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Jan 1, 2020
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774
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Drayton,ND
Does anyone here shoot one? I was originally thinking of doing a CheyTac build but I already have a 700 donor long action in the safe I could use I believe. Or am I wrong and the bolt face won’t work? It’s a 7mm mag action originally. But if the action will work, are any of you here using one? I’m thinking a 28-30” barrel shooting a 300 grain burly should get me way out there with a ton of energy, for much less cost than a cheytac build. Any help and or opinions are very welcome.
I have one I built on a model 70 super grade 300 rum. Only a hunting rifle so I am a bit limited with the 3.6 box. With a 25 inch lilja I am getting 2900 with R26 and a 300gr. Shoots well. In the Remington it should be better yet as you can put in a wyatt,s box and stretch it out. Your old 7 mag action will work fine. Just be sure to order the rum box and your standard bottom metal will work fine. A brake would be a good idea. I have a lot of heavy rifles so recoil doesn,t bother me and I would rather get kicked than blasted. In this rifle you may want to glass the box in solid to help out the stock. If you go with the long barrel 3100 with a 300 would not surprise me. Not for the weak of heart :) To add. Betram is making brass for it now and I like it.
 

WildRose

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Feb 3, 2011
Messages
12,075
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N. Texas and S. Africa
Yes it is, that’s why I’m wondering if the action is strong enough for this cartridge
Should be no problem as far as I know all Rem LA Magnum actions are the same, just need a different follower when you step up to a RUM case.

I have come close to pulling the trigger on both .338 and .375 Rum's but have yet to go there as I'm pretty well covered with the .300 Rum's and .375 Rugers. I keep threatening to build a 28-30" .375 Ruger just to see how far I can stretch it.
 

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