Home Forums Hunting & Shooting Custom Rifles & Wildcats 30/375 Ruger

I'm thinking about rechambering a 300 win mag into a 30/375 Ruger using this reamer


Will probably need to be set back a thread or two but not a complicated thing.

However, dies do seem to be. I will be necking down 375 Ruger brass to 30 caliber and have no clear cut method worked out. To get custom dies they want a fired case which is putting the cart before the horse.

Some ideas

• Get a cheap FL die in 300RCM and set it to just size the neck
• Cut the bottom off a 300 RUM die

Once I have fire formed some cases, then I can send the cases to a die manufacturer.

Any ideas or experience?

Is your action too short to just become a 300 RUM? If not, go with that one.

Of your two options above, I would go with number 1 i.e. 300RCM and simply neck size and would keep right on doing that with the ammo thusly formed.

My action and magazine is too short but I load for 2 of the 300 RUM's and don't really want one. Already have a 338RUM.

The 300 win mag has a case capacity of 87 gr, the 30/375 Ruger will have 93.6 gr and the 300RUM is over 110 grs. The 300 win mag has been my limit of recoil tolerance without a muzzle brake so I think 6 to 7 gr more powder I can learn to live with also.

Hey, I thought this is wildcat forum, do I need a reason?

I think the 35/.375 Ruger would be the ticket!!!

Good points all.

Just using the 300RCM dies should still work. I use 340 WBY dies to make ammo for my slightly longer wildcat 340 Tyrannosaur (338STW or 338/8mm RemMag)and simply screw them down only enough to make or re-size the neck that I need. Used to use 338WinMag dies and those worked OK but I was only able to screw them in a couple of turns to get the neck where I wanted it. BTW, with the 340WBY already out there, my 340 Tyrannosaur makes about as much sense as your 30/375. Only useful in My own mind!!

Deadly on elk and various african plains game, though.

Good luck with your project. Filling in the tiniest niches for modest gains in real world performance is what we are all about!

It would no doubt be a humdinger and may end up a factory round..

I always like the 30-338 as a super round, but hey I am an avid fan of a handloaded 300 H&H, and that makes a lot of todays gunnys roll up in little balls and fret! but the chronograph supports me pretty well...:)

I have used 350 RM dies to form 358 Norma brass from 338 WM brass. Going from 375 to 30 will take a few steps. I tried this with 5 cases that somebody on the campfire was nice enough to send me. First I necked it down in one pass and crushed the case. second I stepped it down using several dies that I had laying around. It worked until I went from 32 cal to 30 cal - then it creased the neck. I purchased a forming set of dies and stepped the next 2 cases down with success. I haven't done anything with the 5th one yet.
You are basicly re-inventing the wheel. Your making a 30 Newton. Don't get me wrong - it is fun - I look forward to getting my 30 Newton complete.