375 RUM or 358/300 RUM???

hhunter318 · January 23, 2011, 04:33 PM

I was brainstorming over many large calibers for a rifle build and was curious about a 375 RUM or a 358/300 RUM. Bullet scarcity isn't an issue as I have a friend with a CNC set up for turning bullets. I want something larger than a 338 but don't really want to go with a Lapua since the 338 RUM can rival the Lapua with the right handloads. So I liked the though of the Ultra mag cases being necked up to .358 or .375. The Cheytacs are too expensive for my taste also. Anyone looked at 505 Gibbs brass prices? Not friendly to the pocket book. Any suggestions throw them at me.

SHR970 · January 24, 2011, 09:00 AM

338 RUM cases are slightly shorter than the rest of the RUM family so they could fit the 300 grain bullets into the standard Rem. 700 long action. If you want a 375 RUM, just buy the cases.

hhunter318 · January 24, 2011, 03:22 PM

Ah, now I see. I was wondering why it was shorter. I'd be single loading anyway. Nothing in the magazine. Wouldn't that eliminate the need for anything longer than the standard long action?

SHR970 · January 26, 2011, 08:06 AM

Assuming you are running a 375 RUM, you can go with the standard 375 brass and load whatever you want...I'm not as sure about anything 358 as I don't have a sample of the longest bullet for caliber offered to test fit in my Remmy. That said, I have worked with two loads so far for my 375..one uses starting loads of H4831SC and the Hornady 225 gr. SP (used to sight in the gun and not as punisher practice), and the other uses a stiff charge of RL22 and Hornady 300 gr BTSP. The latter one is a real attention getter.

Since you seem to be going the way of a custom gun (or at least customized) consider porting, use a real good recoil pad, and go heavy!

One other thing: Hornady's load data is very conservative. Many of their loads do not even reach published starting loads from the powder manufacturers.

hhunter318 · January 26, 2011, 11:37 AM

The only reason I asked about longer actions and single loading was because I was curious about loading some heavy tac bullets such as lost river or woodleighs and wondered if they would fit seated far out. Really action length won't matter unless I decided to use my Win. M70 action from my 7mm Mag. My friend and I were looking to machine an action w/ a fat bolt. Caliber is still pending. I'm looking at .338 EDGE, .358/300 RUM, and .375 RUM. If I don't find what I'm looking for in performance I might open the bolt face up and go to .375 Cheytac. That'll get 'em.

January 23, 2011, 04:33 PM	#1
hhunter318 Senior Member Join Date: September 15, 2010 Posts: 163	375 RUM or 358/300 RUM??? I was brainstorming over many large calibers for a rifle build and was curious about a 375 RUM or a 358/300 RUM. Bullet scarcity isn't an issue as I have a friend with a CNC set up for turning bullets. I want something larger than a 338 but don't really want to go with a Lapua since the 338 RUM can rival the Lapua with the right handloads. So I liked the though of the Ultra mag cases being necked up to .358 or .375. The Cheytacs are too expensive for my taste also. Anyone looked at 505 Gibbs brass prices? Not friendly to the pocket book. Any suggestions throw them at me. Last edited by hhunter318; January 24, 2011 at 02:19 AM.

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January 24, 2011, 09:00 AM	#2
SHR970 Senior Member Join Date: January 24, 2011 Posts: 1,427	338 RUM cases are slightly shorter than the rest of the RUM family so they could fit the 300 grain bullets into the standard Rem. 700 long action. If you want a 375 RUM, just buy the cases.

January 24, 2011, 03:22 PM	#3
hhunter318 Senior Member Join Date: September 15, 2010 Posts: 163	Ah, now I see. I was wondering why it was shorter. I'd be single loading anyway. Nothing in the magazine. Wouldn't that eliminate the need for anything longer than the standard long action?

January 26, 2011, 08:06 AM	#4
SHR970 Senior Member Join Date: January 24, 2011 Posts: 1,427	Assuming you are running a 375 RUM, you can go with the standard 375 brass and load whatever you want...I'm not as sure about anything 358 as I don't have a sample of the longest bullet for caliber offered to test fit in my Remmy. That said, I have worked with two loads so far for my 375..one uses starting loads of H4831SC and the Hornady 225 gr. SP (used to sight in the gun and not as punisher practice), and the other uses a stiff charge of RL22 and Hornady 300 gr BTSP. The latter one is a real attention getter. Since you seem to be going the way of a custom gun (or at least customized) consider porting, use a real good recoil pad, and go heavy! One other thing: Hornady's load data is very conservative. Many of their loads do not even reach published starting loads from the powder manufacturers.

January 26, 2011, 11:37 AM	#5
hhunter318 Senior Member Join Date: September 15, 2010 Posts: 163	The only reason I asked about longer actions and single loading was because I was curious about loading some heavy tac bullets such as lost river or woodleighs and wondered if they would fit seated far out. Really action length won't matter unless I decided to use my Win. M70 action from my 7mm Mag. My friend and I were looking to machine an action w/ a fat bolt. Caliber is still pending. I'm looking at .338 EDGE, .358/300 RUM, and .375 RUM. If I don't find what I'm looking for in performance I might open the bolt face up and go to .375 Cheytac. That'll get 'em.