Turning Down Rim Diameter

Good morning Fellas.

Boys, I am shooting a .45-75 Winchester repro... and my supply of brass has to give out some day. Up here in Canada the brass is like hen's teeth - and while it can be brought across the border - assuming there are still sources for it... it gets very, very pricey.

I'm told that the 50-90 brass can be formed into .45-70 and about the only road block I see for me - is turning down the neck diameter. Do I need a lathe for that? Is there a quick and dirty way to do that?

Also, I will have to trim the brass I have at some point. I have the RCBS trimmer and none of the shell holders fit. Can I file the case down, do you think?

I don't have a full blown machine shop, so any advice you fellas can spare would be sincerely appreciated.

Cheers!

I don't know how much brass you have for your gun, but I can tell you that you'll probably get a minimum of a dozen shots out of each case. I'd think even more, but I haven't loaded mine enough to answer that yet. These cases are like pistol cases....they don't need trimming really and they can be loaded over and over. If you started with a hundred empty cases and loaded each one a dozen times.....you get my drift. Unless you're shooting that gun constantly, you're going to have cases for quite a long time. Enough time to find a few more cases somewhere along the line.

Several make neck turners for the bench rest / varming / long range shooters that are hand powered with a mandrel to support. Look to simclairs K &M ( these 2 come to mind) I made some a few years ago that used a forester style drill press base with the cutter driven in the drill press at low to med speeds. A small mini lathe will do it but accuracy may be iffy. the above tools will give wall thickness that are consistent with in .0002. Another route to go might be neck reaming I don't think its quite as accurate but it is quicker and easier than turning. Here a die holds the case to its outer form in the press and a reamer is ran in with the die supporting it also. this reamer will be a few thousandths of and inch under bullet dia to provide neck tension in standard dies when loading.

Neck turning can be very accurate and precise but getting cutters set dead on and proper mandrel fit can be tricky, I expanded on the turners mandrel and spring back gave a snug fit. setting the cutter can be trial and error, a feeler gage between mandrel and cutter will get you close though. A little sizing lube like imperial die wax on the mandrel case mouth helps turning a lot also.

Check out Redding or RCBS trim dies.

It's normal to be wary of filing on the top of a die, but they're harder than Chinese Algebra and made for it.

You put the die in a press, run the case up, saw/file it off.

Cool guys, thanks for the replies. It appears though, that making the brass from 50 Alaskan is fairly straight forward.... have any of you ever done it?

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Originally Posted by Guy La Pourqe

Cool guys, thanks for the replies. It appears though, that making the brass from 50 Alaskan is fairly straight forward.... have any of you ever done it?

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I've made it from 348 Winchester, so should be close. I trimmed with a tubing cutter, used a copper plumbing reamer to get the thickness right, annealed, ran them through my 45-75 Redding full length sizing die, and loaded them. I'm probably 5 reloadings (I acquired correct brass along the way) but they're still working well.

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Originally Posted by Guy La Pourqe

Cool guys, thanks for the replies. It appears though, that making the brass from 50 Alaskan is fairly straight forward.... have any of you ever done it?

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I used 348 winchester for a Uberti repro - did not ream necks -
) first ran em through my 348 expander die to get any dings out
then trimmed the 348 neck back a bit above required length (luckily! using my process they shrank )
) I anealed
) then went in steps to .375, using a tapered expander plunger made from a HT bolt that fit my Dies
) then 405,
) then I believe I might have annealed again
) finally a 457 expander plunger
)proper trim to length

I cut a bunch of cases too short in the mistaken idea that I would work up a smokeless load around the LEE 340 grain mold and I cut these to suit that boolit and its crimp groove.
never happened! - I get good results with homemade blackpowder using the LEE 405 HB that I modified.

These cases are thick in the neck and a real neat fit in the chamber but that centralises the cases and they blow out quite nice
we got a slight bump in the formed brass where the old shoulder of the 348 was that is a bit tricky with longer boolits (the 405 grainer) so I have an outside swage die I made to just ease out any bumps in the neck that make for sticky chambering.
I cant shoot any boolit fatter than 460 but with the right load, this rifle is scary accurate any time I do my bit.

Starline 50-90 Sharps Straight, is the only donor case with the right base dimension. However the rim of a 50-90 SS is .030 to big in diameter. The best way to trim the rim diameter, would be to find a friend with a lathe. Ideally a lathe with a collet holder. I would recommend turning the rims down first. Before forming the case. 45-75 formed from Starline 50-90 produces necks with .012 neck thickness. This is the dimension of the recent Jamison brass.

Trim the 50-90 case to 1.890
Run a .509 expander in the case, very shallow. Just enough to make it round. This prevents wrinkles from appearing.
Take a existing 45-75 case and use it as a gauge, put a mark on the 50-90 where the middle of the shoulder will be.
Anneal the case at the middle of the shoulder. By doing this it eliminates wrinkling while forming
I lube the case lightly with Imperial size die wax
Screw your sizing die into your press so it touches the case. Now turn the sizing die in a half a turn. Start sizing, remove the case every stroke, and redistribute the lube. Turn the die down a half a turn and repeat. Takes about 20 strokes to form a case. This process is really easy on everything and produces a beautifully formed case.
Cases will then need to be trimmed to 1.880
Rick

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Originally Posted by Rick B

Starline 50-90 Sharps Straight, is the only donor case with the right base dimension. However the rim of a 50-90 SS is .030 to big in diameter. The best way to trim the rim diameter, would be to find a friend with a lathe. Ideally a lathe with a collet holder. I would recommend turning the rims down first. Before forming the case. 45-75 formed from Starline 50-90 produces necks with .012 neck thickness. This is the dimension of the recent Jamison brass.

Trim the 50-90 case to 1.890
Run a .509 expander in the case, very shallow. Just enough to make it round. This prevents wrinkles from appearing.
Take a existing 45-75 case and use it as a gauge, put a mark on the 50-90 where the middle of the shoulder will be.
Anneal the case at the middle of the shoulder. By doing this it eliminates wrinkling while forming
I lube the case lightly with Imperial size die wax
Screw your sizing die into your press so it touches the case. Now turn the sizing die in a half a turn. Start sizing, remove the case every stroke, and redistribute the lube. Turn the die down a half a turn and repeat. Takes about 20 strokes to form a case. This process is really easy on everything and produces a beautifully formed case.
Cases will then need to be trimmed to 1.880
Rick

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Rick
Do you have a measure of those 50/90 at the solid head ?
I was tempted to get some but the case specifications I found on google had them a tad bigger than my uberti chamber - at $3.50 per I was reluctant to buy in case the Sharps brass was made neat to specs -
the 348 brass is ten thou under spec but it works ok - just the cases look a little weird and proly hold a few grains less blackpowder.

The lot of 50-90 SS Starline cases I have average .5597 at the base. The lot of recent
(3 Y.O.) Jamison Brass measures .558.
Rick

That’s funny... it sounded like the 50 Alaskan might be a good way to go too... and it sounds like there’s no lathe work involved....

Jeez I love this lever gun. I put a Lee Shaver on it and took some loads out to chrono... and it stacked them all into 1.6”! I know it was a fluke... but it’s hard not to get excited when that happens. :)

About five years ago I purchased a 1876 Winchester 40-60. Made in 1884. It was a basket case. Had a 1/16” of rust on it, not patina and a barrel with non existent rifling. Rifle was a round barrel not suitable to reline. Sent it to Clearwater Reboring and had the barrel re-bored and rifled to 45 Caliber. Rifle was then chambered to 45-75 WCF. Installed a MVA Mid Range Soule and a Globe Front Sight. Rifle shoots exceptional.
With Jamison Brass no longer in business, the options are

Quality Brass Cartridges
Bertram Brass
Dealer on Etsy, sells reformed 32 Ga. CCC cases
Reformed, Buffalo Arms 50-90 SS to 45-75 WCF, not currently available
Form your own

Donor Cartridge Case Base Diameters
348 Winchester .547
50-90 Sharps Straight Starline .5597
50-110 WCF Starline .5445
32 Gauge CCC .563-.566
Jamison 45-75 WCF 2016 Lot .558

Don’t have a 50 Alaskan to measure, I believe it is in the .544-.547 category.
Cases formed from undersized base dimensions form a Coke bottle appearance, upon firing. 50-90 SS will look normal.
Rick

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Originally Posted by Guy La Pourqe

That’s funny... it sounded like the 50 Alaskan might be a good way to go too... and it sounds like there’s no lathe work involved....

Jeez I love this lever gun. I put a Lee Shaver on it and took some loads out to chrono... and it stacked them all into 1.6”! I know it was a fluke... but it’s hard not to get excited when that happens. :)

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twerent a fluke at all - mine will do it anytime I am up to the mark --- so long as I pay real careful attention to shot cadence - else it will walk up the target as barrel heats.

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Originally Posted by Rick B

The lot of 50-90 SS Starline cases I have average .5597 at the base. The lot of recent
(3 Y.O.) Jamison Brass measures .558.
Rick

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Thanks Rick - appreciate the info.

Ye gods.

Rick... would one of the hobby mini metal lathes be up to the job of turning down case rims? Or should I get the gun rechambered to something else? I have about 125 Jamison cases ... but eventually I will need to do something. Getting brass across the border to me in Canada is another costly nightmare...

Finding 348 Win brass up here is a bear too. I think I will be stuck with either the 50 Alaskan or 50-90...

I believe a small mini lathe would work. However not being a Machinist I would leave a definitive answer to a person that is. A lathe with a collet holder and the right sized collet would allow one to trim over 100 cases an hour.
Rick

Oh crap - there is a section for case forming! I will take this one over there! Thanks again, Rick!