Mounting 338 Win Mag Brass in a Lathe?

[DonMountain]

Unbelievable Success! I just put a large rifle primer in my half-formed case, 16.0 Grains of Unique, filled it to the bottom of the neck with grits (store bought ones, not home ground) and a tuft of Kleenex paper (we are trying to conserve toilet paper) and took it out and fired it. Long case and all. Pulled it out of the rifle chamber, and it looks just like a perfectly formed 43 Spanish case. I mounted it in the case trimmer with a 0.432 (44 Mag) pilot and it was tight enough to trim the case to length (2.25"). It appears that the body of the 338 case is a perfect fit in the 43 Spanish chamber except for the belt. I have a bunch of 370 RCBS mold projectiles already cast up from a bunch of years ago. But they need to be put through the LAM-II to lube and size them. Then its time to fire an actual boolet! Now I need to work on all the other suggestions everyone has given me to be able to form this case more easily and more accurately, including trying the e clips to thicken and enlarge the rim. Thanks everybody for all of your suggestions and keep them coming as I adjust my forming process to make lots more of these.

[1hole]

You're custom fitting cases for your own use, not everyone else's so forget head spacing off the rim; ALL reloaded bottleneck ammo can (and should be) FL sized to headspace off the shoulder. Fit matters and only that insures the round actually fits your chamber. All meaning IF you have enough exposed rim to insure extraction you're in fat city right now!

In my experience, making stepped expander plugs in changes of about 15 thou works well. Anything much greater than that tends to push the necks inside the shoulder!

Proper neck annealing helps when reforming and neck enlarging but getting the brass visibly red destroys its temper and you can't get that back!

[DonMountain]

Now that I know I can reform the case well enough to fit the chamber reasonably, I need to form maybe 25 or 50 of them and then anneal all of them for the next step. Loading consistency and shooting. I resized maybe 200 boolets I had cast 10 years ago from an RCBS 370 FN mold, and sized and lubed in a 0.439" die. So, I got boolets, and now I have at least one case. Now to make more. Although I need to look at better ways to mount a case in the lathe as per suggestions.

[Fishoot]

DonMountain, I just made some .43 Spanish from 338 win mag cases. I have not fired them yet, but plan to load 60-70 grains of 2f in behind a proper cast boolit, add an O-ring to the extraction groove, and let 'er go. I read through some previous posts on making .43 Spanish from mag cases and did some of my own changes. My mandrel is about .441". I cut the mandrel to mount in a 3-jaw chuck and marked the #1 jaw position on the mandrel to orient it the same way for future use. Hopefully, that will reduce the run-out some. The jacobs chuck has no tool, I just butted the jacobs against the back of the case to keep the case from backing off the mandrel. I am thinking of making a tool to mount in the jacobs that would be a mirror image of the case head with a projection which will duplicate the primer pocket. That might further reduce run-out. I found that I had to trim the case necks some to get a boolit loaded case to chamber. A pic of my setup is attached. Feel free to pm me on your efforts.

[DonMountain]

I sized my 338 Win Mag cases and seated a 338 jacketed bullet so that I could chuck the neck in a three-jaw chuck with the primer pocket seated in a bearing mounted center. Then I could easily turn off the belt. After trimming the 338 Win Mag brass to a little over the length of a 43 Spanish brass, the remaining rim allowed me to fire form the case to the chamber using 16.0 grains of UNIQUE, grits for a buffer, and a tuft of Kleenex paper. After fire forming the case, I did a final trim to length and had a perfectly formed case that loaded and shot well. The only problem that I had was extraction after firing. The extractor on the Remington Rolling Block just does not grab the smaller rim resulting from the conversion. So I had to extract them with a screwdriver. But the shape and dimensions of a 338 Win Mag case with the belt cut off are a perfect fit to chamber in the 43 Spanish gun. So, the only problem with them is extraction. After what I learned in this experiment, I am now concentrating on converting some 348 Winchester cases to the 43 Spanish due to the rim being of a good dimension that will allow me to extract them easily. I have already formed a few of these and it looks to me that the harder job of tapering the base of the case results in a better solution for me.

[EDG]

Rotorclip and other C clip manufacturers may make a C clip that can be used as a rim.
Check out the radially installed C clip item C-50

https://www.rotorclip.com/prod_radia...ning_rings.php

[Fishoot]

I had read that the right e-clip would work. I did some measuring and foundwhat I consider to be the best solution for me. McMaster-Carr has what they refer to as: Low-Clearance External Retaining Ring for 1/2" OD, Side-mount, Black-Phosphate Spring Steel, Packs of 50. Their product number is: 97414A660. I ordered some. They fit the case and chamber perfectly! No alteration of the rings required. They even fit the shellholder Lee provides with their .43 Spanish die set. 50 is probably all I will ever need. At $8.84, I think its the perfect solution. All you need to do is orient the clip so it is opposite where you want the extractor to pull the case. This should be far less labor intensive than reforming already precious 348 Win cases or making collars like country gent proposes. (Although I was going the collar way if the clips did not work.) While I was at it, I ordered O-rings for my bullet puller to hold the collets together, some threaded rod in 7/8 x 14 and other goodies.

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.

[Pavogrande]

You might consider dimpling the 348 rim in three places to increase its thickness to .090

[JimB..]

The more I think about it the less I like the assumption that the primer pocket is centered, better to index from the case rim? Maybe turn a small disc from brass or aluminum, cut a rebate that’s a press fit on the case rim, and center drill it and chamfer to fit the live center?

[country gent]

It wouldnt take a lot to make a small cup point center to hold the rim. an old taper or drill with the taper a bearing and piece of steel to make the cup and point from. The cup can be machined in to just mach the rim for this.

A old live center with the bigger point can be taken apart and the old point reworked to a cup point or a new one turned up to just what you want. I would consider a .750 dia end 1" long with the cup Maybe a little smaller dia to give as much tool clearance as possible.

[15meter]

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.

The reason for the spindle taper question is because there are simple, inexpensive collets for the smaller lathes. MT 2 and MT 3. You take the chuck off the lathe and slide the collet into the spindle and draw it up, clamping the part, using a drawbar. The drawbar can be as simple as a piece of threaded rod longer than the spindle, a washer and a nut to draw it up.

Just the collets are available individually and pretty cheap ($8-10 each) Try http://cdcotools.com/, then search for "MT3 Round Collets (Morse Taper #3)". I tried to point to the exact page but it won't let me. They also have MT2 collets. There are other hobby shop vendors that cater to the home shop machinist that have this kind of tooling and will sell to the retail market.

I have a specialized set with holder for my South Bend 9x24 with 3MT head stock it is great for holding small round stock, it is 1/16-1/2" ID by 1/32".



For my Delta wood lathe I use the simple 2MT collet by themselves with a homemade drawbar, great for holding finials and other small detail work.





And I'm like you, this is a hobby, I'll spend time making stuff because I enjoy it. I could go out and just buy the stuff, then I'd have lots of time to watch "The View".........sure, right, right after they issue flying goggles to the porcine aviators

[DonMountain]

The reason for the spindle taper question is because there are simple, inexpensive collets for the smaller lathes. MT 2 and MT 3. You take the chuck off the lathe and slide the collet into the spindle and draw it up, clamping the part, using a drawbar. The drawbar can be as simple as a piece of threaded rod longer than the spindle, a washer and a nut to draw it up.

Well, I never thought about using a collet since it was designed for gripping a straight shaft instead of a tapered cartridge case. I happen to have a whole set of them for holding mills ranging in size from about 1/4" up to 1" I think, plus the threaded shafts to pull them tight. So, how do you get the tapered cases mounted straight in the collet?

[stevenjay1]

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?

First, anneal the neck part of the brass and fire form, This will also set the head space. Second, the rim, this should be the first step. You can enlarge the diameter of the rim by soldering a brass (lacking a better term) ring to the outside of the rim and using a lathe cut to shape This does work but is slow and you need to be gentile when extracting. But it does work. Steve

[15meter]

Well, I never thought about using a collet since it was designed for gripping a straight shaft instead of a tapered cartridge case. I happen to have a whole set of them for holding mills ranging in size from about 1/4" up to 1" I think, plus the threaded shafts to pull them tight. So, how do you get the tapered cases mounted straight in the collet?

Get the case head as close to the collet as you can, at that point it is getting close to being straight, turn on the lathe and if you see any run-out turn it off and try again. I have had a couple walk out of the collet while cutting, just need to tighten it a little more. Rarely do I even see any kind of witness mark on the case and being that close to the head, I have not crushed or dented any cases. I usually just take light cuts. You're just taking off for clearance and with my rolling block and my eyes I doubt if I could detect any accuracy problems with a slightly out of round belt trim job. Give it a try, I think you will like the results.

If you look at the photo, I'm actually cutting away from the head stock, taking advantage of the smaller diameter of the case body for tool clearance and not having to be careful so I don't trim the rim down.

I can usually do 20 cases of just knocking off the belts in ~ 10 minutes.

Next up for me is to reduce the belt on a batch of 375 H&H's down to size to fit in a Rigby 350 Magnum. Did a batch several years ago, need to make enough to last through the shooting season for when we get off this social distancing.

And the 350 Rigby is worth the effort, it's running $5.75 each, when you can find it!

I don't load much during the good weather, that's time for shooting, riding, sailing and other outside kind of stuff. So I keep my self busy during the mud season around here trying to load up enough to last through the shooting season.

[EDG]

To get the case running straight tap it with a small hammer while the lathe is running about 100 to 300 RPM. It takes a little bit of practice to get the RPM and your hand to eye coordination right but you can get them running to within .003 easily.

Well, I never thought about using a collet since it was designed for gripping a straight shaft instead of a tapered cartridge case. I happen to have a whole set of them for holding mills ranging in size from about 1/4" up to 1" I think, plus the threaded shafts to pull them tight. So, how do you get the tapered cases mounted straight in the collet?

[country gent]

Make a dedicated collet for the case. put a .030 shim in the cuts and tighten up on them. bore body taper in collet loosen and remove shims. You case will fit and square naturally and run true. You might look into a straight shank er collet holder. and collet set. These have a big range hold and center very well and an extra collet to bore out wouldn't be expensive. THis could be chucked in lathe mill bench vise or drill press They are handy to have

[GONRA]

Especially for odd cartridge case head verk, GONRA has made many aluminum bar stock RIMMED "split ring" aluminum collet LINERS
that are bored sufficiently to grip bottom of the case body and head. (Just one slit down collet side.)

These slip into some common lathe spindle collet (usually 1/2 or 5/8) you have on hand and locate on the rim.
Can also use in a 3 jaw lathe chuck, but usually not such a nice concentric setup.
Every application's different - use yer imagination..... Sometymes you need 3 slits instead of one, etc. etc.

[15meter]

Well, I never thought about using a collet since it was designed for gripping a straight shaft instead of a tapered cartridge case. I happen to have a whole set of them for holding mills ranging in size from about 1/4" up to 1" I think, plus the threaded shafts to pull them tight. So, how do you get the tapered cases mounted straight in the collet?

Did you ever try just mounting the brass directly into one of your collets? Curious if it worked for you.

[BS2]

[ndnchf]

I'm a bit late to the party, but I thought I add my 2 cents. I've been making extra long .44 S&W American from .303 Savage brass. I made a hollow mandrel with a .003" interference fit and press it into the case mouth. Then set it in a collet in the lathe, supported in the primer pocket with a live center, then turn it to size. I then remove the case and mandrel, clamp the mandrel in a vise and tap case off the mandrel with a rod through the hole. I made a video the other day.

https://youtu.be/iVzb4WopeAM