Martini Cadet conversion

[Stephen Cohen]

A friend of mine has a bubba cadet which will have a good barrel once a couple inches of muzzle end are removed. The project is to up the power of the 310 cadet round by rechambering it to some form of necked down 357 max case, by using some standard die to make the slight bottle neck the case to accept a correct diameter cast bullet of around 160gr, then just running the loaded round through a standard 357 mag size to iron out the body. I agree he could re barrel with a nice new 357 max barrel as I did, but where is the fun in that and he is like a fishes bottom which is water tight. What standard die if any would do what we want with the minimum of fuss. We have thought of the 32 special but consider the shell a bit large. Regards Stephen

[rockrat]

Maybe resize the front with a 30 luger die. Or find a used 30-30 die and have someone cut off part of the base of the die, to get the neck and shoulder, then use your 357mag die.

[webfoot10]

When the Martini's were first imported back in the 60's They were in 32 special
and 32/20. I owned one of each cal. but sold them all. I also had one that was
rebarreled in 218 Bee, but let that one get away also. Wish I had been smart
and bought a few and put them away. They sold for $10 to twenty dollars back
then. But being a kid I didn't think and sold or traded them off. I'd make that
one a 357 mag, and if it didn't work out, ream to 357 maxium. Have fun.
webfoot10

[rking22]

300BO? Could use a neck and throat reamer to make it a long neck with the same body as the 300bo. I have considered the same, using a 1/12 twist and throat for the 31141. There is load data considering the capacity would be the sameish.

[Stephen Cohen]

I see your all on the same page as me with your ideas. webfoot10 we all wish we had the brains to buy a heap of them when we could, hindsight is a wonderful thing, I still have one in 357max which is a joy to use. I think his best bet would to use a blackout sizing die that had the neck opened up to match his barrel calibre, I would personally re barrel to 357mag or max. thanks all for your input. Regards Stephen

[Outpost75]

There are a couple easy options.

The .30 Johnson Special was a .30-30 case shortened to 1.5 inches with no other change.

I've also seen .30-30 brass necked down and the shoulder set back using 7.62x39 dies and leaving the neck a bit longer like a .30-30.

You can use a .30 M1 Carbine reamer like a neck and throater after roughing the chamber with a 7.62x39 or .30-30 reamer stopped short.

On mine I just ran a .30 Carbine reamer into the .310 Cadet chamber and used .32-20 brass with the RCBS 32-120 Cadet Heeled bullet, shot the .320" bullet as-cast and unsized with a case full of 4198. Enough difference in case wall thickness between .30 Carbine and .32-20 that you can use .318-.320 bullets with .32-20 brass blown out straight in the .30 carbine chamber. Pure simplicity.

[barrabruce]

Still have the original 1:20 twist and up to 8mm for short bullets only.

Now a 30 cal 1:10 or 1:12 would be interesting to me at least.

[tommag]

In making 357 max rimless from 223 brass, I found that the body of the 223 was about .006 smaller diameter than the 357. I don't know how much of an issue that would be for you if you used 300bo dies.

[aap2]

I think that a necked-down case will work better that the straight-walled .357 mag case. The .357 mag case with it's lack of taper can really stick in the chamber with the weak extractor of the cadet martini. I had a well-known martini cadet gunsmith convert one of my .310 cadets to .357 mag (reboring the stock barrel since I wanted the rifle to look original) and it was a beautiful rifle but extraction was always sticky with anything but the mildest loads. Despite being reworked the problem remained: the straight case and an extractor system that only pulls the fired case out a short distance is just a bad combo. Gun writer Dean Grennell had the same problem with his martini cadet in .357 mag. Tapered or necked down cases work fine. Just reporting my experience with a .357 martini cadet conversion....

[Stephen Cohen]

Some good ideas here gents. Outpost75 your idea of running 30/30 into 7.62x39 die was one I never thought of and it may well be the choice he makes, aap2 I agree that a bottle neck case will be a better option. My 357 max Cadet can at times be a bit weak with extraction yet it throws 357 mag brass to hell and back, I doubt if the shell only being extracted enough to grab with fingers will be a problem to a re loader. The whole point of the exercise is a light handy close range deer rifle and only one shot will be all he will get in the country he hunts. Regards Stephen