Coming soon: How to form 45-90 into .43 Mauser

WARNING: THE FOLLOWING POST CONTAINS OUTSIDE THE BOX IDEAS AND LOAD DATA THAT DIFFER FROM TRADITIONAL RELOADING PRACTICES. USE AT YOUR OWN RISK


First up is initial sizing. This Jamison 45-90 has thick tapered walls that expand too much with the Lee expander rod, it will not chamber once resized. Simply size without the rod, chambers smooth and gives us an inside neck diameter of .444. Can't ask for better than that as our bullets are .446 to .447. After forming, trim to length you desire. Leaving the brass as is 45-90 length causes the mouths to crimp excessively on bullet seating even with the die backed out.

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The original scope of this how to was to utilize a shop press with a custom machined die (pictured below) to swage the A base design into the 45-90. The die is perfect, but my press has too much slop and presses crooked every time. I scrapped the idea after 4 ruined shells. I will try again after shimming my press or just using a 1 ton arbor press. It swages quite easily.

http://i393.photobucket.com/albums/p...c.jpg~original


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My remedy to allow the flat base 45-90 rim to chamber properly and sit flat against the bolt was simple. Remove a little material from the ejector tip. It still has plenty of protrusion when pushed forward on extraction to kick the shell into orbit. It still works with proper A bases too. I don't particularly care for this fix. But.....this picture is in the retracted position and gives us a flat face for normal cases. THIS RIFLE IS A MIXMASTER AND NO VALUE WAS LOST HERE. If your rifle is a matching piece or you just prefer to mod another part, you can buy ejectors from Old Western Scrounger for around $12 on ebay and Gunbroker.

http://i393.photobucket.com/albums/p...n.jpg~original

Now onto loading and fire forming. I experimented with 2 powders and various charge weights of each. The pictures below illustrate my findings. Your chamber may vary. These were all fired with 405 grain bullets. The H4198 worked great at all charge levels of 28 to 30 grains. I will be settling on 30.5 to 31 for my future range loads. They formed well except the main body area did not fully expand, this is an eye sore for me. The light loads of unique expanded the main bodies even less. I then thought, we're dealing with low pressures here. Why not fully anneal the whole damn thing head and all? So I did, and 14g unique gave 100% expansion. The last 1/4" of the head is solid brass and will never form.

http://i393.photobucket.com/albums/p...8.jpg~original

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That's it folks, pretty easy. I do recommend the full case anneal as some have had splitting issues. The Jamison is the cheapest .45-90 at $1 each but is by no means cheap, it has been great stuff to work with. I don't really like modding the rifle, i always prefer to mod the brass or equipment first. In this case no value was lost and I gained a lot of flexibility in being able to shoot the heck out of it which I fully intend to.

http://i393.photobucket.com/albums/p...f.jpg~original

:D This sounds like fun.I`ll saddle up and ride along.
Good luck.Have fun.Be safe.
Leo

got a question for y'all - just got back from a range session with my 71/84 mauser carbine. when I miked the bases of the formed 43 mauser (from 45-90), the case heads didn't expand at all! started out at .504 and never moved. a little further up the case, it blew out to .516, which is the appropriate chamber dimension at that spot. the load was the lyman 350 grain .446 boolit, pc, over 30 grains imr4198. shot to point of aim at 200 meters (actually shot about an 8" group). no signs of over or under-pressure on the cases.
any ideas? is this a problem? I know the chamber is correct because I have shot proper 43 mauser brass and they mike at .516 at the base.

Quote:

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Originally Posted by dogmower

got a question for y'all - just got back from a range session with my 71/84 mauser carbine. when I miked the bases of the formed 43 mauser (from 45-90), the case heads didn't expand at all! started out at .504 and never moved. a little further up the case, it blew out to .516, which is the appropriate chamber dimension at that spot. the load was the lyman 350 grain .446 boolit, pc, over 30 grains imr4198. shot to point of aim at 200 meters (actually shot about an 8" group). no signs of over or under-pressure on the cases.
any ideas? is this a problem? I know the chamber is correct because I have shot proper 43 mauser brass and they mike at .516 at the base.

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If the head expanded, the primer pockets would be loose and the brass would then be scrap.

How do you deal with the rim thickness? crimp it thicker or just headspace off the neck cone?

dogmower-504 to 516 is no big deal, 0.006 thou per side. BUT ... You might want or need to center up the cases before firing. If you can tape the under side (bottom) you will get a better looking case. May cause trouble with extractor. REMEMBER - after firing, your 45-90 case head is NOT concentric with your case mouth. This might causes trouble in neck sizing or seating. Go slow and let the case center up on the tool before the base get rigid. Also don't full resize unless you have too. That blown out wall will be a weak spot.

carry on

Interested in this I have 50 factory cases and the only new ones I can find are Bertram, I've had bad luck with Bertram poor quality for the premium price you pay.

My base forming die I had made by a forum member here is on it's way to me, I will post up the how to when it arrives.

Making "A" base cases (52mm long) from 45-70's there were side split failures that I didn't get to stop. The increase in diameter wasn't much but the hoop dimension was that increase x pi so it added up and bit me. Needed to do a better pre-form annealing and a different choice of loads to reduce the quick bump.
Back then I reduced the rim diameters by hand. Take a little off, check, take a little off, check again...

Updated

Well gunfreak25, sorry that the rim die wasn't working in your press, but I'm glad to see the progress!

Just a little range report. It showed promise at first but as the temps heated up (the ammo too) my ignition went to pot. Hang fires, etc. It shows promise though, this was 31 grains of H4198 behind a 350 grain soft lead bullet crimped. Going to use some kapok to keep the powder charge at the base next time. Ammo tilted forward resulted in hang fires, ammo tilted up (muzzle up) gave good ignition, so too much inconsistency to work without a filler. Extremely clean burning, light recoil and shot 15 inches high which should equate to 1400FPS or so. No leading too! Will post next range report. This brass was also un-fire-formed so that could have also contributed to any inconsistencies.


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I've had good luck with Dacron pillow stuffing for a filler in my 9.3x74. Does make a mess on your shooting range. One old pillow's worth will last a few lifetimes.

I test fired a few today with 1 to 1.5 grains of cotton ball fiber over the powder to take up the airspace, not a tight fit against the powder just enough to keep things from sloshing about too much. Worked great so I have another batch loaded up for testing.

Good work sir! The 11.15 X 60R is a fun cartridge as well as a good one for medium game. I have a German double rifle so chambered that was a real education to work up loads that regulated. Hope the "A" base swage die works for you.

I don't know how it would work in a bolt rifle but I do know guys who have made a die that would allow the rim to be bent forward for use in single shot and double rifles. The die has a step and one takes a steel rod near case mouth ID, inserts it into the case and gently taps it until the rim is bent far enough forward until it spaces on the rim. It takes very little. I've used the same method for Buffalo Arms 9 X 57R brass made from 444 Marlin that was a bit too thin rimmed. Perhaps a bit primitive but effective.

I am having a blast with this rifle, no primers backing out and cases look great. I have settled on 31.5 grains of H4198 with a 2 grain fluff of cotton to keep the powder from sloshing about. Velocity must be around 1400-1500 with these 350 grain bullets because the sights are spot on at 250 meters which is the lowest available setting. A 12 o clock hold at the 300 meter boar puts em right in the middle.

I am waiting on a paper patch mold from Arclight and will get some more targets posted when I can get out.

This is a great old thread and I am pouring over all that I can find on these. Is the Mauser A rim needed for M71 too or just the 71/84? I have been told there are differences with the bolt and ejector.

Thanks, BlackPowderLove for bringing this back to life. I missed it the first time around. I was thinking that I had not gotten my 43 Argentine out for awhile and might test drive it with some duplex loads I did up with Nobades help. This looks like a good project to try.

I made a tool for bending the rim for headspace. Would only work for one shot because at the next primer seating it would bend it flat again. Now I get headspace by jamming the boolit in to the rifling.

Quote:

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Originally Posted by Pavogrande

How do you deal with the rim thickness? crimp it thicker or just headspace off the neck cone?

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Have a friend with a lathe or shop make a steel die to form the A-base. It is simply a 1 Inch diameter steel rod about 3/4 inch long. With a lathe or a couple flat faced drills form a cup on the flat face of the die body that is the mirror image of an A-base. The larger diameter is the same as the diameter of the shell rim. Make it the same depth as the thickness of the rim. In the centre make another cup that is a bit larger in diameter than the diameter of an A-base. The depth is the same as the raised portion of an A-based shell. This die should be approximately the mirror image of the A-base.
Now to form the A-base using your 45/70 brass you need to find a bolt that just slides into the neck of the shell. The bolt should be flat on the bottom. Now give this bolt a couple hits with a heavy hammer. That should form the A-base. Do one brass first and cycle it through your gun.
I have made 100 cases this way out of 45/90 cases with no losses. Yes it's crude but it works well.