Martini Cadet to .357

[Watermelon Wine]

Not sure at what point a late reply becomes bumping an old thread, but I would like to be kept in the loop for how this project progresses as well. It sounds like here in Australia we're slightly luckier with martini pricing. (Should be thankful for small mercies I guess!)

Martini conversion is popular here. Although the .310s have a small following, there are more people with .310s without cartridges than cartridges without .310's... if that makes sense. ...and a whole heap with conversions.
I own three at present, including the oft-discussed .44 rem mag version (middle) a .22 "K" Hornet (top) and .22lr (bottom, obviously...)

All were 'bubba'd' looong before I got my hands on them... if it makes a difference...
I paid between $125 and $150 for each of them.

The history of these things can become convoluted to chase, but two are marked 'BSA' and one: 'WW Greener". Some have a kangaroo stamped on the top of the action, and some don't. Here in Australia, it seems like a lot of the 'converted' ones passed through the hands of 'Sportco', and are known as "Sportco Martinis".

Two of Sportco's favorite tricks were to rebarrel to 22 Hornet, by affixing a .223" (rimfire) barrel with a 1 in 16" left hand twist and reaming to hornet, and, converting to .22lr by fitting the same barrel and grinding down the 'horns' of the closing lever in such a way that the 'closed' position of the breech-block aligns the standard 'center-fire' firing pin with the lower rim of the .22lr cartridge case. Thus it is 'theoretically' possible to return a converted action to centre-fire by either building up the horns, or fitting a non-modified lever.
Unfortunately this second system leaves the block not lining up with the side walls of the action body which is a little unsightly after it's been brought to your attention... I ground the sidewalls down to be flush with the top of the block, so it's probably too late for me...

As a side note, my good mate 'Bruce' (but we call him 'Bluey', on account of his red hair) assured me that the left hand twist was an absolute necessity for making a northern hemisphere rifle shoot worth a damn in the southern hemisphere... something to do with the coriolis effect going the wrong way making the little boolits dizzy and all...

Anyhow, for what it's worth to those that follow, the .44 mag is intact, and beautiful, after 5+ boxes of full power factory loads. (240 grain jacketed at 1740fps) There are three basic camps;
One camp says: "Why risk it?".
Another camp counters with: (Insert famous name here) performed destructive testing and failed to blow one at 65,000psi (this I believe might be true but the name escapes me for quotation purposes... it was one of the "Ackleys" of the world however.)
The third camp (my gunsmith included) will happily tell you which maker made the strongest actions and only convert those ones.
I shoot mine happily, and yet, if I did it again I would opt for an ever so slightly smaller case, either .32-20 for plinking or .357 magnum for hunting. I suppose the very fact that THAT is in the back of my mind puts me in the first camp...

[Ballistics in Scotland]

I don't believe there is any difference in quality or reliability in the Greener or BSA actions, or indeed in the August Francotte Belgian actions , stamped AF in a circle on the internal parts, which were used for the .297/230 Australian Cadet rifles.

I have never heard of the .44 Magnum conversion causing an explosion, or indeed any other conversion. Some people report, and others don't, that it can cause the chamber, now with rather thin walls, to expand and cause difficult extraction. It may depend on the tightness of the barrel threads. I think any rifle chamber will expand, but if the threads fit very closely they may stop it expandinh beyond the elastic limit from which it can spring back to its original shape.

Pistol loads, which normally have to develop all their velocity within a few inches, may not be the best for a rifle. The handloader can use a slower powder to develop less peak pressure, but keep more of it as the bullet proceeds down the bore.

I know of Ackley's 65,000 psi test, and all they prove is that one rifle of similar design to yours didn't blow up when it fired such a charge. Impairment which can later cause failure after more use can result, and it proves nothing at all about another action. The Cadet is a pretty strong action, but all rifles should be capable of withstanding a proof load far in excess of service pressures. There are people who reload wildcat cartridges to a level little if any below that, and the Cadet is certainly unsafe for doing that.

The theory about drift is of very little relevance to real-life shooting. One form of drift is dependent only on the direction of the rifling twist, and it is of some importance to very long-range target shooters. It isn't proportional to distance, and would be far worse in your one-mile Hornet than at a thousand yards. Then there is another form of drift, the coriolis effect, which is almost entirely irrelevant to all smallarms shooting, but is in different directions in the northern and southern hemispheres.

If you have left-hand rifling tiny and microscopic add up in the southern hemisphere. But in the northern hemisphere your bullet deviates by the difference between them. With a right-hand twist the reverse happens. That is why the British very sensibly designed the Lee-Enfield with left-hand twist, in the belief that major wars would be in Europe. As it happens they then fought in South Africa the only war in which long-range musketry was the dominant weapon.

But all of this only matters if the tiny one matters, which is a most improbable thing with any Cadet. Besides that, your friend got the direction wrong. Sounds like it was just something to make conversation with.

[Watermelon Wine]

G'day Ballistics!

Great to hear from someone who knows a bit about martinis!

Your observation about the possibility of a loose-cut tenon thread allowing 'stretch' over insufficiently supported sections of chamber in some big bore conversions sounds like it might have some merit.

For some reason hearing of bulged chambers introduced the idea that it might be the relatively 'petite' frame of the small frame martini that was stretching in some instances. This didn't make sense as I had always assumed that the combined ring strength of the barrel and action combined MUST have been calculated to be sufficient (plus a significant safety margin) any number of times or it would NEVER be done... These two conflicting ideas have been festering in my subconscious for some time waiting for some light. Thanks!

I mostly shoot cast plinking loads in my .44 so by comparison the factory loads must feel like 'proof' loads to the poor old girl anyway!

The left-hand twist comment was indeed 'tongue in cheek' and I tried to mark it as such with a 'wink' and a 'pulling your chain' emoticon. I don't always manage to make my attempts at humour clear on these forumy-thingies. My bad. Sorry.

It may have been accidental but I was really quite pleased to learn that there was ACTUALLY a difference between left and right hand spin in the northern and southern hemispheres. I had always assumed that whatever you gained when facing north would be lost in similar amounts when facing south, so didn't really worry about it all that much... particularly when shooting my hornet!!!

Back on topic, for those trying to 'accurise' martinis, I've read on other forums that it's important to maintain a small gap between the forend and the front of the action.

Cheers! WMW

[Ballistics in Scotland]

The sides of the true Cadet action are quite thin. I have never heard of them giving way, but I suppose it could be achieved by something foolish. If it is a source of worry, the latest versions of the BSA rimfire target rifles have much thicker sides. This also makes them look better with a stock and forend which aren't very narrow. If I was doing this again I might use one of these and mill the sides a little thinner, while leaving flanges adjoining the wood, like a lever-action Winchester.

The internal action frame is mostly non-load bearing at the moment of firing. It simply forms a pad between the block pivot and the receiver.

It is important not to have erratic contact between the forend and receiver. A small gap is one way of doing this, and contact released as the barrel heats up is likely to harm accuracy. Another way is to inlet a piece of rubber sheet into the rear surface of the receiver, so that pressure is maintained, and close to the same, at all times.

[Hooker53]

Great I fo here. I would love to see a photo or two of the rubber sheet conversion on the action. Good to see you around Eric.

Roy
Hooker53

[KCSO]

32-20 yes 357 NO! Too much pressure for a gun made for 1/2 the pressure of a 357.

[Ballistics in Scotland]

While the 65,000psi figure mentioned above is far above a safe working pressure for regular use, people do rebarrel Cadets and their rimfire successors for various much higher pressure cartridges than the original .310 round. I have heard of no serious accidents, and the uncertain possibility of a swollen chamber with the larger diameter cases is a huge disappointment but very unlikely to become dangerous. Like the Browning Winchesters, the Cadet will stand a lot more pressure than it needed to do when introduced.

In the UK we have the greyhound-sized roe deer, which provides some of the most challenging stalking and is exceptionally good to eat. The law in England requires a certain energy, or in Scotland a certain velocity, which points to the .222 Remington family. While I have wildcatted the .357 Maximum into a good one in the past, my choice would now be the German 5.6x50R. But if it wasn't for the law I could scarcely wish for a better or safer Cadet cartridge than the .357.

[MaxJon]

I have a .310 cadet unmolested which is a beauty! Shoots great too! I would love one in .357magnum because I have .358 swage dies! Never ending, cheap bullets!!

[Stephen Cohen]

My BSA Martini is in 357 Maximum and I have no problems with pressure or accuracy. I do have to watch what projectiles I use as some don't like to chamber unless they are seated deeper. I have loaded 140 gr XTP to just over 2500fps, 158 gr xtp to 2400fps and 180 xtp to just over 2200fps with no pressure problems, the cast loads in both 158 and 180gr have been driven at similar velocities with very good accuracy in the 1 1/4 to 1 1/2 inch at 100 metres. I would hunt any game in this Country short of Buffalo with this rifle, in fact it is my new deer rifle of choice, Regards Stephen.

[Ballistics in Scotland]

There are a couple of sources for Cadet Martinis which might be of interest. I have bought several firearms over the years from this Australian auction house, whose online catalogue for their 29th April sale is now available. They have numerous Cadets, British and Francotte. As I said earlier, the Francotte action is of good quality, but the barrel is a bit slender, when it is a .297/.230, for reboring to anything larger, and that cartridge isn't much of a return on the trouble it is to make.

https://www.australianarmsauctions.com/next-auction/

https://www.australianarmsauctions.com/faq/

I believe they still operate under an Australia Post ban on firearms in ordinary mail, but there is information on how they can get a gun to you in their FAQ. I heard it rumoured many years ago that BATF in the US know a .310 Cadet can't be a pre-1899 antique, but a .297/.230 Francotte can be. If they haven't forgotten.

On this French auction website someone is selling ol factory stock Francotte receivers which have never been used, for 25 euros, under the title "boitier Martini". Other parts are harder to find, but the action frame can be fabricated with silver solder.

https://www.naturabuy.fr/

[john.k]

Those who go on about small diameter tenon threads and strength should take a 1895 Marlin in 45/70 apart....the thin.ness of the chamber and reciever ring is scary...to me at least...Cadet Martinis are a dime a dozen as it were nowdays,and a heap were handed in at last years amnesty......which I suspect is the source of the auction haul.....all handins were to licenced dealers,who could either keep the gun or recieve a fee for processing same on behalf of the cops........Furthermore,if you load excessive pressure in a Cadet,the block will jam shut,because you have to shear the cratered primer metal ......222Rimmed is possibly the best conversion for a Cadet,and cases are available from Bertram.

[Drm50]

I've owned several Martini BSA that have been rebarreled and a few in original 310. I had a 357
that a friend had built. Stock and rebarreled, no sights set up for scope mounts. It shot good but
I didn't like the scope and no sights. A local gunsmith built a lot of Martinis in 60s. I also had a
Ackley Jet which is a 357 necked to 22. A hot little round, built by same smith. My favorite was
a 218 Bee that had Lyman reciever sight and target front.

[Ballistics in Scotland]

Those who go on about small diameter tenon threads and strength should take a 1895 Marlin in 45/70 apart....the thin.ness of the chamber and reciever ring is scary...to me at least...Cadet Martinis are a dime a dozen as it were nowdays,and a heap were handed in at last years amnesty......which I suspect is the source of the auction haul.....all handins were to licenced dealers,who could either keep the gun or recieve a fee for processing same on behalf of the cops........Furthermore,if you load excessive pressure in a Cadet,the block will jam shut,because you have to shear the cratered primer metal ......222Rimmed is possibly the best conversion for a Cadet,and cases are available from Bertram.

I'm sure the .222 Rimmed is one of the best for this rifle, but so is the German 5.6x50R, with cases available from RWS or Sellier and Bellot. The economics may be different outside Australia. In the UK Bertram .222 Rimmed costs £2.03 a time.

[john.k]

Hello,BIS...I should mention that my 222r has a small notch cut in the top of the chamber which admits the blade of a small screwdriver...my take on the rimless extractor....While I admire the quality of the little guns,their main fault is that they are too little.......not a fault for a 12yr old cadet,obviously.Its sad to see so many destroyed in the recent amnesty,Lithgow 22s too,but thats the way it is.

[Ballistics in Scotland]

Yes, and the military Martini is unnecessarily wide, to accommodate its large cartridge, which is both difficult to load well with smokeless powders, and is very expensive in components and dies. I wish someone had made a Martini action a little narrower in the block and a little thicker in the sides.

[Blue2]

Not bragging- just built up a collection over the years.
Personal small frame martinis--22lr,22 Win RF mag, 22 Hornet,22K. Hornet, 218 Bee,17 Ackley Bee,223 Rem., 5.6x50R,225 Win, 30 Herret, .357 Mag. ,30Cadet,222R. I was thinking of chambering up a spare barrel in 17HMR for the 22mag.
Why? It's an addiction! I mostly just shoot the 22lr and the std. 22 Hornet. The 17 Ackley is great fun to shoot.The .225 is the most challenging one to shoot well. It requires a hand held shooting technique rather than resting it on a forward rest. The barrel vibrations from being supported on a rest give less satisfactory groups than supporting with a light hand held grip. The less aggressive cartridges all perform well when supported on a forward rest.

[MaxJon]

Love your addiction, I could easily join you!

[Ballistics in Scotland]

If you do a search on the French www.naturabuy.com for boitier Martini, you will find one or two sellers who offer apparently unused factory receivers for both the Cadet and military-size Martinis. They are pretty free and easy about export. Although not identified as such they appear to be of the Francotte internal-frame design, possibly copies. There are some other parts for the large Martinis, but for the Cadet size there is usually nothing but extractors. The small ones have a cylindrical crosspiece in the receiver instead of a stud in the action frame, for location purposes. But for the sort of obsessive we see here - you know who you are - something could be done.

[Polyanna]

Regarding conversion of Martini Cadet to 357 Magnum .I acquired a Cadet that had been converted to 357 Mag /8mm- along with reaming dies for the barrel plus forming and resizing 357 an 38 Special brass. The 8mm is .323 diameter which allowed using the original barrel. - It was very accurate, and I have since reamed two additional rifes to 357/8mm . the only other modification was adjustng the extractor to fit the357 brass. I did not modify the firing pin. With standard 8mm bullets and recast from tire weights all are extremely accurate

[Rapier]

The 357 Super Mag conversion takes a bit more work. The original barrel cuts get the chamber/extractor-ejector, needs to be cut, the bolt need to have a cup bushing installed with black Lcktight, 6,000 psi shear strength, so the hammer stops on the bolt/frame and not on the bushing, firing pin is reduced in diameter and hole drilled to match, about the same diameter as a 700 firing pin / hole combination. Load with 358 rifle bullets only, I use 180s and 200 RN or the RCBS 200 cast plain base powder coated, and H-110 with 205m primers. Some I have done required a bit of polishing to easily feed. Scope, should be a long body, to assist feeding and ejection. A decent trigger job helps a good bit. I glass bed the barrel solid to the forend with two forend screws, using cut off and drilled brass as escutcheons. A paper thickness free space between the forearm and receiver. A 6" streight section of barrel to mount the forend and scope, scope bases are 541 Remington bases.
This is the Walnut gun, top and the Switch Barrel 357 Super Mag that I made, on the bottom with a Big Leaf Maple stock. Neither have given one moment of trouble. A 357 Mag is not much compared to the Super Mag or 225 WM. Both shoot sub 1/2" at 100.
The 357 SuperMag is the original name of the (Max). That camber will allow 38 Spl, 357 Mag and....