Sizing .458’s down for Mauser model 71’s .454 bore?

[mkj4him]

I think you will find the chamber wont accept anything over a.449/.450 bullet. When I first got started with my 71 the first bullet I used was a Lee 45-70 405 hollow base, I sized it down to .451 in a lee push through. After loading the cartridge I removed the decapping pin from the sizer die and ran the loaded case into the sizer to swage the neck down enough to chamber freely. It worked fairly well.

I am currently working on a paper patch load and a heeled bullet load.

They are a lot of fun but kind of a pain to get going

Please share what bullet mold you’re using for the paper patch and the heeled bullet? I am thinking about getting the old west molds 43 Mauser mold. Any experience with it or have you heard good things? I have a whole boatload of Lee push through sizers on the way I should take care of any of my sizing needs

[mkj4him]

I got the Old West Moulds 43 Mauser brass mold and the Lee 446 and 448 sizers. I cast up several with my softish Keel Lead. I think I’m going to have to add tin because I can’t get out the wrinkles.

[whisler]

I have read that brass molds like to run hot. How hot are you running?

[mkj4him]

I got to 750. Mold maker says try 750-800. No more than 800. Guess I’ll try 800. ��*♂️

[Gobeyond]

Yes old west currently has one mold left. I use .448 in my 43 Mauser. I can seat them by hand in a fired case. Lyman and rcbs have 446 -447 in their molds. But a custom mold from accurate molds you can get what you want. I think a 448 will obturate big enough in my 454 groove. Had some accuracy. Still testing.

[mkj4him]

Sounds like we have the same groove measurements. I sized mine to 448 as well, after powder coating. Using Lee die set and Lee universal case mouth beller they seated just fine. I used an rcbs 44 mag seating die as a crimp die to just remove the mouth bell. Chambered fine and slid back out with a slight jiggle (since my extractor broke.)
I had to full length size the fourteen 348 Win cases I have since they were formed to 43 Spanish or something similar. My sized cases chambered and fired fine. Used ram rod to tap out fired fire formed case. From there I just neck sized the case and it loaded and chambered fine. I haven’t tried loading without any sizing yet but may give that a try as well.
I loaded mine to OAL of 3” per COTW. Charge was 31 grains IMR 4198. Winchester LRP. Havent shot on paper yet.