Tuesday, April 17, 2018

A dive into the insanity of obsolete cartridge loading

I wrote once before about forming brass from one cartridge to make brass for another, but this one gets a bit more involved than most.

Meet the .310 Cadet
It's a rimmed case used in the Australian Cadet, a small-frame Martini used as a training rifle.  There are lots of these around, and a friend has a very pretty one, but you cannot buy loaded ammo for it.  A search indicates that you can form brass for it from .32-20, but there are a couple of caveats:
You will probably have to thin the case rim.
You will have to full-length size the brass in a suitable die.
You will have to trim it to length.
It uses an odd bullet.

So, where to start... my process was to
Resize the cases,
Thin the rims,
Cut to just above finished length,
final trim and deburr.
Friend had a set of .310 dies, so lubed the cases, pulled the deprime/neck expander assembly and resized the brass.  I've read it can be done in a .30 Carbine sizing die, will have to try that sometime.  Reason for resizing first is .32-20 is a necked case, and I wanted the straight body to fit into the lathe chuck.

I've read of people clamping the case in a drill press and using a file to cut the rim down.  It should work, but that'd be a long way to do it.  If you have access to a lathe, I'd suggest that.*

This being a somewhat worn little lathe, it took some fiddling to get the procedure right.  That was stick the case into the chuck; use a caliper to set each case with the same amount sticking out;

use a facing bit to cut away at the front of the rim

until had a thickness of .046-.050", which proved to work nicely with the rifle in question.

To trim, I used a small Harbor Freight cutoff saw(originally bought to make .300 Blackout cases from .223).  Took a piece of hardwood dowel, sanded it to a slip-fit in the case, adjusted it in the vise so it would cut at the right length

and went to it.  Two things:
First, it took two cuts: the first to get rid of about half the length, the second to make the finished length.

Second, you have to hold the saw in position with one hand and rotate the case with the other, and you will make a cut into the dowel.  But it gives you a pretty consistent length with minimal deburring needed.  Which is good, because the walls of these cases are thin.
Note: if I were going to make a lot of these cases, I'd get a piece of aluminum rod, turn it to fit, and use that for the mandrel.

Trimming to exact length is tricky primarily because there are different lengths listed.  I found this on one loading site

and that Kynoch cartridge up at the top measures 1.120", so I went with that. 

.32-20 case sized, rim thinned, cut to length
Yes, the mouth on the last needs deburring.  And be careful doing it; the walls of these cases are thin, and it's easy to damage the mouth.

For the bullet, RCBS makes a mold to cast the proper heeled bullet at a nominal 120 grains, and friend has one.  These were used as-cast(15-1 as that's what was in the melter), and tumble-lubed with this modified Lee Liquid Alox.**  Some searching around found a variety of loads, the primary for starting off seems to be 4.0 to 4.5 of Unique; this being a new one to me, I started with 4.0.

Original and new cartridge

They were tried out over the weekend; all went bang, accuracy seemed quite good
Top group was five rounds, holding on the bottom of the white bullseye; lower group is ten rounds, holding on the 5.  Range was 30 yards, with forearm resting on the bench top.  I'll add that this little rifle had quite good sights, the rear adjustable for both windage and elevation.

The case mouth was not crimped onto the heel; the die won't do that, so these were a tight press-fit into the neck.  After having been fired the cases were formed to the chamber, and the bullet can be seated by thumb pressure.  I'd hate to carry them out hunting that way unless in some suitable case, but it seems to work well for general target shooting.  

There was no sign of leading or other nastiness in the bore, so the lube did its job.  And I think this counts as success.

I'll have some more on the rifle and cartridge later.

*The other method I've read of is swaging: take a piece of flat steel plate and drill two holes: one for the case body to fit through, the other, slightly larger, for the rim.  That one has to be shallow enough that you can put a flat punch on top, whack it, and swage the rim down.

**I've used this lube on many different bullets for rifle and pistol, and it works quite well.  


Anonymous said...

I shot one of these fine little rifles that the owner had the original barrel rechambered to 32 Winchester special. it shot great.

Anonymous said...

I got one too.

Shoots two one inch groups about 4 inches apart, at 100 yards. Something must be loose, I guess.

I trimmed the rim using an aluminum mandrel inside the case, and a live center in the primer pocket - about 15 thousandths off the front edge, IIRC.

I just thumb seat the bullets in cases without resizing.

There was an article about this rifle/caliber about ten years ago in ... Rifle or maybe Handloader. He used Rooster Red lube, Dental Wax gas checks, and Universal Clays powder to get gong-ringing accuracy at 600 yards. Cast heeled bullets from wheel weights.

0007 said...

An easier fix might be to simply re-chamber for the 32-20,which is what was done to one of the several I have, heh, heh, also .219 Zipper, .357 Mag, .222R, and 7mm TCU.

Firehand said...

He wants to keep it original. And that's something I'm going to touch on when I can make time to write the next post.

Anonymous said...

Looks a bit like the .32 Rimfire, only a bit longer. One of my old aquaintences had a single shot T/C Contender carbine barrel in .30 Carbine. We shot it - it was a lot of fun, but not a precision shooter. About 2 MOA was the best we could get out of it.

Anonymous said...

to: 0007

Re-chambering to 32-20 was done to thousands of these, and because the barrel is closer to .320 than to .30, they typically didn't shoot well. The bullet just rattled down the bore.

The .310 diameter was the heeled part that went inside the case mouth. The largest diameter (as cast) is .325, near the grease groove.

I suppose you could re-chamber to 32-20, plus a bit (around the case mouth) and use .310 style bullets, and that might work (and be accurate). For the cost of the custim chamber reamer, you could re-barrel in anything that you like.

Critter said...

As a fan of obscure cartridges myself, I salute you, sir. My obsession these days is the Remington family of proprietary rounds.