Mounting 338 Win Mag Brass in a Lathe?

I am looking at taking another stab at producing 43 Spanish cases for my Remington Rolling Block and have read suggestions that 338 Win Mag brass could be used by cutting off the belt and reworking the rim of the case. My question is for the machinists in the group, how would I mount one of these tapered cases in my lathe? I have a 3-jaw chuck, and flat base plates to mount things too. My tool mount has a swivel top so I can mount and run tooling in a taper for about 6", which would allow me to easily follow the taper of the case with a cutting tool.

Use a piece of 1" round stock 1 1/2" long turn true on outside cut 2 1/8" grooves 1/8" deep ( on a side). drill and bore for the cases body taper. cut into 3 pieces and use o rings to hold together. ( think shell holder for a inertia puller). A lip on the front will help locate on the chuck jaws.

Find a drill bit that is a slip fit in the case mouth. Chuck the neck in the three jaw chuck and crank it down on the drill/neck combo. Use the tail stock with a standard or "live" center in the primer pocket and go to work.

I am not a machinist by any stretch of the imagination, but I think if you seat a .338 bullet then you could tighten the chuck on the neck of the case. Might be kind of hard on the bullet after ten or twenty go rounds, but hey its probably a red coated pretender anyway.

Robert

Buy a Wilson case trimmer case holder for the .338.

Tap the .338 cases into the case holder until the case locks in place.

It is better to chuck it in a 1" collet in your lathe.

If you do not have a collet set you can chuck it in a 3 jaw chuck.

https://lewilson.com/rifle-case-holders/

You might be able to take a 338 size die and put in your 3 jaw, with the decapping stem removed. Lube a case and tap lightly into the die, trim off belt , then take a 1/4 brass rod and run thru your headstock into the size die and tap out the case

Do what Bud said. If you can't find a drill bit, simply turn a mandrel to fit the case mouth. Slip the mandrel into the case mouth, slip that into your 3 jaw chuck, tighten it slightly, turn your live center from the tail stock into the primer pocket, tighten all down, gently, and go to work. Works perfect...and it ain't rocket science.....and it's a LOT less work than any of the other suggested means.....and it's as cheap as you'll find.

What Sharps said, the mandrel is your friend.

3 jaw chucks are not very precise, but if you chuck up a piece of bar and then turn the mandrel and never remove it from the chuck it’ll center the work well. You’ll also want to prep the brass as well as you can before mounting it, the more concentric the casemouth is, the better.

The mandrel is the way to go but file a sharp screw driver tip on the mandrel and push the brass firmly on the mandrel with the live center. This helps keep it from spinning on the mandrel.
Also, if you mark the mandrel to one of the chuck jaws, you can reuse it later. Resize the brass first to get it as straight and uniform as possible.

I made 43 Mauser out of 300 and 458 mag brass. I removed my 3 jaw chuck and used a collet, worked perfectly for trimming the belts off.

It appears some of us are doing it a bit differently. Definitely prep your brass. The mandrels I make are a slightly snug fit and I slip neck and all into the chuck. That is I actually close the chuck jaws on the case neck I've never deformed a case and obviously it never slips. I also expect any of the ways will work just fine one a fella figgers out how to make them work.

Well, I attempted a quicky solution of turning off the 338 Win Mag belt for a trial to see if I can form the whole 43 Spanish case. I sized a new case, seated a 338 bullet in the neck, chucked it up in a three-jaw chuck with the primer pocket seated in a live center in the tailstock. Set the tool holder to travel at the same slope as the case, and turned off the belt without any problems. Although the primer pocket appears to be a little off center so it didn't come out perfect. So, on to the next problem. I trimmed down the case to a little longer than needed in my case trimmer with a 338 guide, and then resized the case using the 43 Spanish die with the expander removed. And the case fits into the rifle chamber all the way to the rim as it should. So now, I have the problem of expanding the case mouth from .338 to 0.439". I guess I need to turn some case expanders on the lathe? And the case seats ok in the rifle, but the rim is not large enough to catch the extractor. Any way to fix that?

nobody asked what spindle taper is your lathe.
I am surprised at that.
3MT?
4MT?
Can you run 5C emergency collet?
And what is a 'flat base plate' as said in the OP?
Is that a face plate?
Which way you trying to hold it? by the neck or by the base.?

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Originally Posted by DonMountain

Well, I attempted a quicky solution of turning off the 338 Win Mag belt for a trial to see if I can form the whole 43 Spanish case. I sized a new case, seated a 338 bullet in the neck, chucked it up in a three-jaw chuck with the primer pocket seated in a live center in the tailstock. Set the tool holder to travel at the same slope as the case, and turned off the belt without any problems. Although the primer pocket appears to be a little off center so it didn't come out perfect. So, on to the next problem. I trimmed down the case to a little longer than needed in my case trimmer with a 338 guide, and then resized the case using the 43 Spanish die with the expander removed. And the case fits into the rifle chamber all the way to the rim as it should. So now, I have the problem of expanding the case mouth from .338 to 0.439". I guess I need to turn some case expanders on the lathe? And the case seats ok in the rifle, but the rim is not large enough to catch the extractor. Any way to fix that?

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yeah,
https://www.trackofthewolf.com/Categ...ASE-43-SPANISH

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Originally Posted by kens

yeah,
https://www.trackofthewolf.com/Categ...ASE-43-SPANISH

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Its because of their $3.39 price tag plus shipping I decided to try making an acceptable case on my old lathe. I have 20 cases I bought 25 or 30 years ago at a high price that still have the 348 headstamp. So, someone made the ones I have out of 348 casings. And I am not a machinist. As for your questions in the previous message. Why would you want to know what Morris Taper my headstock has? If I remember correctly its a #2. Or maybe thats on the tailstock. And I used the term "base" instead of "face", I apologize to all of you experienced machinists. And how I mounted the 338 casing in the lathe was detailed in the message you quoted above. And all of this casting projectiles and reloading and shooting is just a hobby for all of us. So, I am just trying to hobby up some cases to continue shooting this ancient Remington Rolling Block rifle. If I had lots of money, I would just buy a rifle and buy ammo for it over at the gun store.

Did a bunch of 30-30 turning down the case rims to .473 standard '06 size for a friend who was playing around with a small ring mauser project. Made a slightly oversized spud which went in the 3 jaw and live center in the tail stock. Since friction is the only thing that keeps the case from rotating light cuts only. Did a light chamfer cut somewhat like that on 30--40 Krag cases. What became of the project I really don't know. Since the rims were sized to a normal .473 head size guess he was was trying to make a bolt action 30-30. Not an unknown project since there were a few gun manufacturers who did make bolt actioned repeaters for the 30-30. Winchester,Savage Stevens and Remington. Frank

I have my experimental case with the belt turned off, and resized to a point where the shoulder seats at the correct length in the chamber. Should I try trimming the case length all the way down to the book length and then fireform it since I don't have a good expander button? And what would I load to do the fireforming if this would be safe?

Don’t you snap an e-clip into the rimless groove to make the “rim” on the case? I would do that, then fireform with a small powder charge and Cream of Wheat.

My usual rule is, dies for going to smaller calibers, expanding mandrel for no more than two calibers larger, fireforming for any larger expansion.

I’m setting up to make some .44-77s from .348 cases, just to see if I can, so this thread is interesting.

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Originally Posted by Bent Ramrod

Don’t you snap an e-clip into the rimless groove to make the “rim” on the case? I would do that, then fireform with a small powder charge and Cream of Wheat.

My usual rule is, dies for going to smaller calibers, expanding mandrel for no more than two calibers larger, fireforming for any larger expansion.

I’m setting up to make some .44-77s from .348 cases, just to see if I can, so this thread is interesting.

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Thanks for your help Bent Ramrod. After I cut the belt off this 338 Win Mag case, the remaining rim that is approximately the same diameter as the belt, projects enough from the case to headspace the case. Although I am not sure if the small section of shoulder formed with the 43 Spanish sizing die isn't also maintaining headspace. I still have a projecting section of the original 338 case neck length still there, but my case is still 0.075" longer than the finished case should be. I was thinking of leaving it long until I had expanded the case neck to the proper size. But if I fireform the case, since I don't seem to have proper case neck expanders, I risk the problem of expanding the case mouth into the rifling. But maybe that wouldn't be a problem if I didn't have a bullet seated in the case?

See what the rim thickness is on 338 wm and 43 spanish is. if you have the room by some e clips and they should thicken the "rim" and add dia. If they are big on the od turning them will probably take carbide. They are tough. the .532 dia would be roughly 17/32 dia so a tap could be made to thread a piece of brass round stock then the rims threaded. and installed a 17/32 thread at around 40 tpi should do well here. Even better would be to turn the existing rim off and make the new rim over sized thread on and turn to size after installed., this will give much more thread length and a shoulder to seat against.