I know its not gunsmithing but what brass would be best suited to make solid turned cases for low pressure loads? Im thinkning of turning some cases for an old pinfire shotgun.

Brett

I'm glad you mentioned for low pressure because brass cases for high pressure and pistol cases is a science that they take very serious. The brass has to be tempered and that can only be done through working it.

I would look for brass that is alloyed like modern cases are today and I believe they are a mixture of brass, copper, and zinc. Hope that helps some.

Brass is a mixture of copper and zinc !!
Actually 'cartridge brass' is the name of a 70Cu-30Zn alloy which is the most ductile of the brasses. Normally cases are made by 'back extrusion' .The hardness of the different sections of the case are different and must be maintained.
I've never made them but you'd have to start with hardened brass and the last step would be to anneal the neck. I'm not sure how hard it would be ,perhaps 3/4 or full hard.

Depends on just how low the pressure is as to whether you would need pre-hardened brass or not.

At one time most cartridges in this country were made of "brass" with slightly more Cu (72%) than it now has, and therefore less Zn (28%). That changed right about WWII. The older commonly used cartridge brass was more ductile than the current brass is. As a result, it fire-formed better and easier. The downside is it was less "strong". But it was still plenty strong for cartridges which tended to be loaded hot...such as the .219 Improved Zipper.

Prior to that, back in black powder cartridge days, some of the smaller cartridge cases were even more copper and less zinc, and were even softer...especially in rimfires.

There are many "bad" aspects to using cases which are turned on lathes, but one of the "good" aspects is that the case walls don't HAVE to taper internally, and can be whatever thickness one thinks is needed to house small powder charges. As one isn't producing millions of them, more brass can be used to make a given number of cases without running up the materials cost significantly.

In fact, it is a lot easier to make untapered walls which are thicker than normal, and have not only better cases than thin untapered ones would be, but potentially less waste caused by spoiled ones.

For relatively weak pistols, that is no big deal, as one is not trying to get umpteen feet per second from their usually soft lead porjectiles. Or, at least, they shouldn't be trying to do that.

Certainly I wouldn't attempt to make cases on a lathe for high intensity cartridges. It can be done, but the brass seldom proves entirely satisfactory for repeat shots, and the safety margin is much smaller..

To clarify the Pinfire is an old shotgun. Charges will be black powder only. Pressures less than 10000 PSI. Probably more like 5-6,000.

The problem I can see with cartridge brass, or -70-30 is that I cant seem to find any solid rod to machine. Im guessing that is because it is extruded.

I was hoping that someone would know a brass that was suitable and could be found in large enough rod sizes to machine into 12 bore cases. Companies like RMC are doing it so I know it can be done. It looks like yellow brass is 65-35 copper-zince and has similar properties like tensile and yield strengths.

Brett

Well, there's always more than one way to skin a cat.

I'm not going to advise you as to what you SHOULD do, but there a couple of approaches I would recommend.

The first thing I would try is going to my closest metals supplier, usually listed in the yellow pages under "Steel" or "Metals". I would ask them not for cartridge brass, but for 70/30 brass, and would inquire as to whether they can find any 3/4" diameter rods of that material....in 4 or 6 foot lengths from their industrial contacts.

My second thought would turn to making dual metal shells....with the head made of steel, with the primer, powder, and "burn" chambers all internal to the head. Then I'd take a look at whether I could thread the inside of that head to take 65/35 brass for the body of the shell (if need be).

Pressures are going to be lower once the burn has moved part way down the length of the shell, so you could possibly make only half or slightly more of the shell of brass? That should leave enough to seal THE CHAMBER AND BORE well, I'd SUSPECT.

While I was at it, I'd also think through just how big the powder reservoir/burn volume in the shell head should be. The thicker I could make the head of a bi-metallic case, the stronger I could probably make the threads where the brass portion of the case joined the head.

None of those things might be practical for you, but IF you can't find the diameter of cartridge brass you want/need, there has to be an alternate way to skin that cat. You just have to fantasize/dream/think long enough to find it.

I have heard of people simply "converting" fired centrefire shot gun cases to pinfire in the past but no more than that.

About what AC said about a two metal case sounds good when you figure in the cost of a solid brass bar. You're going to be wasting most of that brass which is too expensive. Maybe finding it in a suitable size tubing would be more effective and making the head of steel such as AC mentioned. Metals are all pretty expensive currently.

Cartridge brass is 70-30 or alloy 260.Probably easier to find it under alloy 260.

Like mete said look for CD260 but Cartridge brass is a common name too. People in the metals industry are not thrown by Cartridge brass, Yellow brass, Naval bronze.

Thanks for the tips. Looks like Ill have to go in to the supplier in the next few days to see what i can find.

If you do decide to make cases from bar stock, don't forget to get your lathe chip pan immaculately clean BEFORE you start. Then any chips you create can be gathered up and sold back to the metals dealer as just what it is, scrap pure cartridge brass. At least you'll cut your costs a bit by doing that.

BTW, two more things. I always find it more productive to ask for expensive metals in person, instead of over the phone. If you look solid and take the time to drive over there, they usually feel you are a little more certain to come back for the stuff after they have bought and paid for it & the shipping. And if they need a deposit, then you can speed up the process by being there to give them one.

Secondly, in Canada sometimes folks seem to act a little funny if they know anything they are selling is going to be used in or for a gun. Most western Canadians are okay with that, but one never knows up front. So I wouldn't use the term cartridge brass, until you know him better...and what if the person you deal with is a female employee? No, I'd personally use either the 260 brass term, or 70/30 brass. And if they asked me what I want it for, I'd say I was going to make some hi-pressure gas fittings....which IS true.

Or you could call Rocky Mountain Cartridge and ask if they can make cases for pinfire... They can easily do some very cool things for guns!

http://www.rockymountaincartridge.com/

The Handbook of Cartridge Conversions has a whole section on turned and tubed cases. Quite a good discussion onhow to and their limits.

Thanks Art.

Thats the Donnely book you are talking about right?

Thanks Art.

Thats the Donnelly book you are talking about right?

Does anyone here have a source for 260 brass in round stock? I have never found it, tube and plate are all that is available. If 260 is what you want to use then the only option that I am aware of is to buy plate and then cut out rectangles and turn them round.
I am not sure of this but I am willing to bet that Dave at RMC does not use 260 brass for this very reason. If he does I would love to know where he is getting it.