Home Forums Hunting & Shooting Single Shots Charting new territory with a .310 Martini Cadet

I recently purchased a nice old Cadet, and during the course of studying it, discovered that the bore slugged .321, which falls within the typical range for these rifles. The brass for this cartridge is frequently made by trimming 32-20 cases back to 1.120" and thinning the rim about .010". Many Cadets will chamber a shortened 32-20 case with no thinning of the rim. I found this to be the case with my example.

The .310 Cadet cartridge was designed to use a heeled bullet of .323" diameter with a .310" heel.

Just out of curiosity, I decided to insert a .322" diameter "O" buckshot in the mouth of one of the trimmed cases to see if it would chamber,...and was surprised to find that it did!

The outside diameter of the mouth of the cartridge measures .334 after it's expanded by the seating of the .322" ball, yet the cartridge readily chambers.

This convinced me that I could use heel-less, full diameter bullets in my cartridges and make the loading process as simple as for any conventional modern cartridge.

I started digging around for any bullets I might have on hand which matched the groove diameter of the Martini and came up with some old Yugoslavian military surplus cartridges in 8mm Mauser. After pulling one of the bullets, I found that it measured .322" diameter,..close enough.

I stuck the bullet in the lathe and cut it down to .585" length, then loaded it butt forward in the shortened 32-20 case. The shortened bullet weighs 115 grains. The Yugoslavian bullets are more or less a boattail design and the tapered tail section of the bullet, when loaded forward, makes a tidy truncated cone, cup point projectile for the .310 Cadet.

I was a bit concerned about shooting a jacketed bullet with exposed lead now on both ends, but the bullet jacket is rolled over and crimped around the core at the base (now the nose) of the bullet, and there was another ring .4" up from the base where the jacket had been crimped into the core. Because of this, I doubted that the Cadet round would generate enough pressure or velocity to separate the jacket from the core.

After recovering the fired bullet, I discovered that it demonstrated no sign of core separation. In fact, except for the engraving of the rifling, the bullet demonstrated no distortion at all. The thick jacket of the military bullet will probably cause them to perform like solids at any velocity the .310 cartridge is capable of producing.

I loaded a cartridge with 4 grains of Unique and fired it into a stack of magazines just to test its function. The load gave a modest report and didn't penetrate very far, but the test was successful in proving that full diameter. 322" bullets can be used in my Martini with no need for a heel.

Now that that's been established, I'm looking forward to working up some loads with WW296 to see what this bullet is capable of from the little rifle.

Interesting post. I've been in the market for one of these rifles. I was reading where some have taken the 357 mag cases and necked down to accept the 8mm or so bullets. It seems to give a little more punch than the 32-20 in the long run.

Yeah,..I've heard of that also, but as I understand it, it would require a rechambering of the barrel. The .310 chamber is too small to accept the diameter of a .357 case. Essentially, it's a wildcat conversion.

Good to know. I'm interested in hearing how it performs.

Personally, I'd like to try about as heavy a bullet as I can get it to shoot with some accuracy. I know it will never be a 32 Special. Thought maybe a sort of "Whisper-like" concept may be the ticket.

I've seen load data where 120 grain bullets have been pushed to 1500 fps with Red Dot. My thinking is, if a propellant as fast as Red Dot can get a 120 to 1500, the slower powders, like 296 or 4227 can get them to about 1650 at the same pressure.

Of course, that load was shooting slippery cast bullets, and my bullet has a heavy copper jacket,...so it's an apples and oranges situation.

I guess "Be careful" goes without saying...when in doubt, you can always tie it to a tire.

lol,...I'm definitely going to start small and work up the loads in small increments. This is a situation that definitely calls for it. Like the title of the thread says, "charting new territory".

But that's what makes it interesting.

a story in a magazine back in the 1960's got me interested in the Cadet-the writer chambered a Martini Cadet in 32 spec.-he found out immediately that the heavier bullets keyholed- later I rebarreled several of these actions, one for myself in 17 imp.bee, it was a terrific little rifle-I have one that I chambered many years ago in 32-40-I know that the factory bulllets keyhole, but I purchased online an old Ideal bullet mold (32359) that casts a 120gr. bullet-it stabilizes and shoots nice little groups-I would highly recommend this chambering if you can find a bullet mold such as this

I think I'm going to enjoy playing with it in its original chambering now that I've learned that heeled bullets are an un-necessary nuisance.

I've sucessfully loaded and fired 3 different projectiles of .322 diameter through it so far.

I've ordered a proper set of dies for it, but they're going to take a while to arrive. Now, I'm putting together cartridges with a hodgepodge of dies that I have around and had to make a neck expanded die to open the case mouths up to .320.

Good article in "Rifle" Magazine on the .310 Greener Cadet and .300 Sherwood by Ross Seyfried; it's called "Little Rifles, Long Range" and is on pp. 38-45 of Rifle #199, January 2002. Covers handloads for the .310, how to make cases, etc.

I think this is going to be my standard. It's a 32-20 case trimmed to 1.120" with a bullet that started life as a 170 grain .322" cast projectile intended for an 8mm Mauser. I lathe turned the base off of the bullets until they weighed 125 grains, then stuffed them into the case after fireforming it to the Martini chamber with a roundball load.



I've been working it up in small increments with some of the slower handgun propellants and have it shooting fairly hard. No excess pressure signs yet. The primers are still nicely rounded at the edges and I've already got it barking loud enough that I don't feel comfortable touching any more off in the basement.

re Bristoe
sounds like you made up your mind to stick with the 32-20 case-nothing wrong with that-back in the 60's, Vic's in Galveston,TX, sold these guns by the hundreds, at 15.00 a pop-ammo was hard to get, and I was told that you could almost kill a mockingbird with it!-I would love to know what they are bringing nowdays-I have one that was rebored,chambered and rifled to 357mag-when you fire it, it sounds like a Zulu blow gun!-these little rifles are known for their fast lock time and are much stronger than most people think-as I said before, I rebarreled and rechambered many of them, and I would never recommend the 32 spec. as a choice for these little rifles-I only said I had heard it had been done-anything on the 357 case (22 jet,256 or anything on the 218 bee case) works wonderfully-a brother-in-law had one in 223 that had a spring-loaded ejector for the rimless case-it worked flawlessly-this rifle, and my 17 Ack.imp., fired thousands of rounds without a hitch-the reason that I chambered this last rifle for the 32-40 was that it is a low pressure round and is tapered all the way-also,brass is easily formed from 30-30's which are easily obtained, even though a mite short-I use this last one as a knock around rifle on the ranch-wouldn't change it for anything-I know you will be as happy with yours-these Cadets just seem to do something for you-if you feel the need for a hundred or so of these 120's I'm casting let me know, I'll send you some free of charge-wishing you lots of fun, and good groups

That's a very generous offer, oldgunsmith. I've done quite a bit of casting. I know how much labor there is in a hundred bullets.

As for the power level of these "mini big bore" rifles, a glance through a couple of reloading manuals shows the .357 magnum getting about 1450 fps out of a 6" barreled revolver with 125 grain bullets.

I have no doubt that I'm going to be able to get that and then some out of the little .310 Cadet.

I've been talking to some guys on a Martini Cadet forum about what I'm doing, and they're all wagging their fingers at me and telling me what a bad person I am. They're a bit of the traditional sort. All they want to do is load a 120 grain, heeled, round nose bullet over a few grains of Red Dot or Unique and pop it along at 1200 fps.

Ain't nuthin' wrong with that, I suppose, but when I look at that strong little Martini action attached to a 24" barrel, my thoughts turn to WW296, H110, and AA1680.

Hey Bristoe, Before you get your loads too hot, have somebody bush your firing pin-I'm sure you know this-being old, I'm sorta set in my ways-although I used 4198 in my 17, I have pretty well stuck with 2400 and 4759 when I can get it, for most of the cartridges I use in the Martini's-never having loaded for the original round, you are way ahead of me already-drop a line and let me know how it shoots

Bristoe,

Not that it matters much, but in turning the bullets in your lathe...how consistent are the bullet weights?

If you cut them all to the same length, they're about as consistent as any cast bullet can get.

I set the lathe up with a collet stop and a saddle stop and every bullet is trimmed to within .001" of the other.

I fabricated a collet insert made of delrin (an industrial plastic),..pretty much a collet within a collet, to hold the bullet without marring it,..and once you get both of the locating stops set up, it's as simple as inserting a bullet into the collet, closing the collet, and throwing a lever.

If anything, they're more consistent after the trimming than they were before.

Yeah,..I've heard of the firing pin issue and I'm probably going to get that situation taken care of before it's all said and done.

I think I could do it myself if I had some detailed instructions and some dimensions on what the diameter of the firing pin hole is supposed to be.

I've read this and that about it. Some say that you also have to go with a smaller diameter firing pin, too.

I can't see why you'd have to do both.

Seems to me if you reduce the clearance between the diameter of the pin and the hole the problem would be solved,...and you can do that just by installing a bushing with a hole just big enough for the firing pin to pass through.

What do you think about it?

Here's the one I'm playing with. It's a BSA.

Looks pretty clean. Some I've been looking over have been a bit questionable but are just listed as C&R's and not necessarily shooters. I would like to have a shooter. Otherwise, I'll be trying to use it as a donor for something else. And, I don't need that right now.

Yeah,..I found this one on gunbroker. I was surprised at how nice it was. The seller said it had a dark bore. It didn't have a dark bore,...it had a dirty bore. I ran a mop with Flitz on it through the bore a few times and it lit up like a new dime.