Base Swaging

[wyowillys46]

Does anyone here have experience in swaging the base/head on cartridge cases? I'm looking for data regarding brass springback, mouth-first versus base-first swaging, resulting cartridge elongation, friction using steel versus carbide, etc. The engineering texts I have don't have much data.

This seems to be a subject that suffers from a lack of available information. Despite my research, not much information seems to exist on this subject here or elsewhere on the web. I have a copy of Nonte's book coming so I'm hoping there will be some there.

[skeettx]

More data please
From what to what?
Now many mils?

I have a set of RCBS base swaging dies for .473 cases.

Also I have used diesel roll pins for making 43 Spanish out of 348 Win cases
BUT it takes a 20 ton hydraulic press

Mike

p.s. in MOST cases, it is easier and cheaper to find the parent cartridge brass

[rancher1913]

pm btsniper, he can answer your size/spring back question. when you swag brass into bullets you usually squeeze it down and the dies have built in "spring back" accounted for. its very hard to size up and get it right, much easier to size down.

[AntiqueSledMan]

Hello wyowillys46,

I have formed 32 S&W to 32 Rimfire specs, going from .339" to .3167".
I didn't worry about the primer pocket shrinking as I planned on drilling
through the base for a .27 cal. Power tool cartridge as primer.
I did it with a home built tool shown below.

AntiqueSledMan,

[Hanzy4200]

I attempted to swage down some .357 SIG for use in 8mm Nambu, but it was a bit beyond my experience level. Another member here, far beyond me in skill, knocked it out without even trying.

[garandsrus]

I have converted 357 Sig and 40 S&W to 8 Nambu. It takes case lube and a strong press. Reducing the diameter in two steps would reduce the pressure needed on each step by quite a bit.

[dtknowles]

The amount of spring back is a function of the amount of elastic strain vs. plastic strain. You need a stress strain curve for the brass at that temper. Since you don't know the temper math will only get you so close. We know that if the brass is of annealed temper the spring back is much less than if it is a harder temper.

This is what I found on the web.



It shows that brass goes plastic at right around 40 ksi with the elastic strain being around 0.0035" That would be the amount of spring back I would expect it the brass was a HO1 temper.

Tim

[garandsrus]

That’s probably about right. I definitely had more spring back in the brass than I expected with the first dies I made. I didn’t really expect any since the case head is solid.

If you make the die .005 small, you can always enlarge it after you measure the resized cases.

[EDG]

What you are talking about is developing a manufacturing process.
The best you can do is make dies and conduct experiments. Different batches of brass will have different mechanical properties so you will get differing results with differing lots of brass.

Each lot of brass may require a different die and a different process.

[wyowillys46]

Thanks for the responses and for that cartridge brass stress strain curve Tim. Don't know why I didn't think to search specifically for that. As a side note, I'm guessing that the curve, like most, is showing strain in the conventional unitless sense. Meaning change in length (delta L) over original length (L).

I received Nonte's book last week, and it's a great resource. A hydraulic swaging press will go on my list of projects. Hopefully soon.

[dtknowles]

Thanks for the responses and for that cartridge brass stress strain curve Tim. Don't know why I didn't think to search specifically for that. As a side note, I'm guessing that the curve, like most, is showing strain in the conventional unitless sense. Meaning change in length (delta L) over original length (L).


I received Nonte's book last week, and it's a great resource. A hydraulic swaging press will go on my list of projects. Hopefully soon.

There was no reference to the test method. It could be inches per inch, should be. That would be an important point since I am guessing the cases you are swaging are less than an inch so the spring back would be proportionally less. Maybe half as much as the three thou I wrote.

Tim

[NoZombies]

When I'm making ladybug brass I'm going from .278 (ish) to .246 in a single step. My sizing 'ring' is .245 in diameter to get the finished size of .246. The 'ring' is only .090 long. The shorter I made the sizing ring, the easier the process is, with the .090 length requiring no intermediate steps, and having a very high success rate compared to previously attempted methods. It increases the length of the brass by apx .015-.020. I end up with a small section of brass I have to lathe off to get the case head above the rim (the solid head) to diameter. Since I'm cutting the rim and an extractor clearance groove anyways I gave up my attempts to 'shear' the last part off.

I support the primer pocket and flash hole with a base punch that I made for the purpose, and I don't have to rework them after forming the brass. The leade into the sizing ring is about 1/8" radius.

The brass is driven back out of the die using a punch, and is ready for the lathe work.

[EDG]

I don't mean to discourage you but here is what I tried.

I had case head separations with a #4 Mark1 Lee Enfield. Some of the separation was caused because the chamber was much larger in diameter than USA made brass. To get around this I tried making .303 brass out of .444 Marlin brass. MY chamber was ,460 in diameter in front of the rim. The .444 brass was .464 in front of the rim. I found that the .44 Mag steel sizer was about .458 so I used one of the many dies you find orphaned due to use of a carbide die. I managed to split 2 of the steel .44 mag dies just trying to reduce the .444 brass by .004.

The brass only swaged down about .002 and I turned the rest off of the case heads. It amde good brass for the .303 but it was a lot of work.
Large reductions of case heads by swaging don't appear to be very feasible.

[salpal48]

If your looking to swage to the bottom of cases weather Rimmed or Rimless, that will be a difficult task. as you know the base is thick. I have found it would be better to use a Base Shaving Die . This die will shave cases up to .005 off. Ch4d has them. They are diameter specific but they do the job. rimless cases will cut off Clean but Rimmed you will have to Clean them up. The Ch shell holder pushes the case completely to the rim, then must be Pushed out with a rod
Simple and easy with No spring back

[wyowillys46]

I have a lathe and can trim bases should I need; however, my goal is to move brass, not remove it. The plan will be to have some swaging dies made from 2" diameter tool steel and make up a simple hydraulic press that they will mount in using Nonte's book as a guide. My limiting factor is fitting this in with the other things I have going on.