I'm thinking of rebarreling a Martini Cadet to 7-30 Waters.

It has already been altered with the armory barrel rechambered to 32 Win Spl., and doesn't shoot (or extract) well with anything I've tried in it.

Anybody here have experience with rebarreling a Cadet to Waters or 30-30, and fitting a peep of some sort? Any lessons or advice?

You asked for advice and experience...I'm offering opinion. The Martini Cadet was designed and built to be a diminutive delight in mild "rook" cartridges. There is the radius of the breechblock (long rounds need to be shoehorned into the chamber), there is the lack of wall thickness in the barrel/chamber juncture, enter pressure numbers and cartridge base diameter, there is the issue of altering the extractor to fit the selected chambering. I do not see the point. Yes, you can put a Mopar hemi in a VW, the question being, is the best use for the hemi? Is it the best use for the VW? In the end it's your rifle, your decision...if you make your Cadet into a deer rifle, like all compromises, it may do both jobs but neither job really well.

7 TCU Might be a better option

Why?

Bob Snapp, who was the Cadet custom rifle guru, used a Cadet in 7x30 Waters as his deer rifle, so it can be made to work fine. The action istself is very strong. The issues are access to the chamber (Mr. Snapp mounted an extended eye relief scope, which removed the problem of fumbling under the scope to load and unload the rifle) and, the Cadet's weakest point, which is the relatively thin portion of the chamber under the barrel threads, which can cause expansion of those the portion of the chamber under those threads when high pressure loads are fired. The .30-30 family, which includes the 7x30, operates (at least in factory level loads - hot rodders may not get the same results) at a low enough pressure that it doesn't create that problem. The .222 family works because the case diameter is smaller, providing thicker walls under the barrel threads.

I spoke at length with Mr. Snapp about the potential to build a stalking rifle on the Cadet action and he was very supportive of the idea. You do need to bush the breech face and install a reduced diameter firing pin, as you'll get primer flow into the firing pin hole in the breech face, locking the action up tight, from both the .30-30 family and the .222 family if you don't. I found that out when I bought a Cadet chambered for a .20 caliber wildcat on a blown out .218 Bee case. Got about 3300 fps with lighter weight bullets, but my first shot locked the breech block up tight. I sent it to Mr. Snapp, who told me he put it in a vice, had his wife lean on the lever and used a wooden dowel with a hammer driving it to force the breech block down and shear the extruded primer off.

Now THAT is some helpful information. Need for a bushed and smaller firing pin in particular. Thanks!

The 7TCU is based on the 223 Rem case and thus it has a much smaller case diameter than any of the rounds based on the 30-30 case. That will allow for more metal around the chamber area, and also with it being a much smaller case overall, it might be easier to load and unload in the Martini. The smaller 222/223 family case head also imparts less pressure back against the breech block upon firing. Same reasoning why T/C could chamber high intensity rounds like the 223 Rem in their original Contender handguns and why they wouldn't chamber rounds like the 7mm-08 in the Contender. Yes, the 7-30 Waters isn't in the same PSI league as the 7mm-0-8 but a 7mmTCU would come close to equaling the ballistics of the 7-30 Waters in a rifle. John Haviland out of Missoula wrote an article for Wolfe Publications about loading for the 7TCU in a rifle. It appeared in either Rifle or Handloader magazine and I have a copy somewhere...

I took my 310 Martini and barreled it and made it into a 357 maximum. Works very well with extend eye relief scope. It kills deer with ease if I do my part.

Evening, I've had a few, two hornets, and an improved hornet, and one 218 bee. All we're a lot of fun!!! I always thought a martini in 6.8 or 6mm x 6.8 or maybe 22 or 6mm ppc would be fun. Rimmed rounds are easier for extractor mods. 357 or 357 max, maybe neck the max down to your favourite caliber??? 30-30 shortened & necked down?? I always wanted one in 17x357, a sorta rimmed fireball. Lots of options, keep us posted. Bill out. 👣🐾👣🐾🇨🇦

Just thinking that it would be easier to feed and eject. I have a 17 Ackley Hornet and a 20X223 Improved and have friends that have several other cartridge configurations. Slimmer shorter cartridges are easier to fed and eject if you have any intention of mounting a standard eye relief scope. For other sighting options like scout scopes or peep sights might not matter.

If you do decide to go with a .222 case family wildcat, let me suggest something built on a 5.6x50 Magnum or the earlier rimmed version, the 5.6x50R. That will give you the maximum capacity in a .222 family case. Something necked to .25. 6.5 mm or .284 would make a great 200 yard deer rifle.

Or left alone in .22 would make a good deer rifle, with proper bullets.

Well heck, why don't I just build a fast twist (1-in-9) .223 and whack everything up to mossy-horned whitetail bucks with it using Barnes 62 gr. pills to 200 yards? I'd need a scope (and would really prefer a LER scope so my stubby fingers don't need to fight their way under a tight scope), but still.... I might actually be able to resell it that way in my dotage.

Perfectly logical but logic has no place on the 'campfire - this is the home of RIFLE LOONIES!

I think with most Cadet rechambers, the bullet is either way undersized and rattling down the barrel, or being squeezed to death.

Have you even slugged the barrel? My .310 slugs to .318" and so I cast/size to .319"

That's because .310 is the bore diameter, not the groove diameter. I've seen .310 Cadets with groove diameters as large as .321. That's the reason that rechambering them to .32-20 didn't work well. The .32-20 is a .312-313 groove diameter and the bullets were not filling out to the rifling.

One solution to that I found was using hollow base wadcutter .32 bullets. They seemed to bump out to fill the grooves, and accuracy was ok at relatively close ranges.

And black powder would help bump those HB wadcutters up to bore size, if you don't mind a little cleaning and "air pollution"! (Cadets aren't the nicest rifles to clean, as I suspect more than a few Ozzie cadets found out....).

6.5 or 7mm TCU ought to be the "cats meow" as they say!

A tapered case will feed easier than a cylindrical case that must be directly in line with the chamber to enter.

Bruce

If 7-30 Waters was the go-to for the Cadet authority Bob Snapp, I'm comfortable with giving it a try. I'm ordering a chambered barrel from Douglas.

I'm hoping to fit it with a peep, but not sure the vintage BSA No. 7A or No. 8 are as refined as I'd like. Other suggestions?

If you don't mind drilling and tapping the receiver, you could use one of the Lyman sights, which are quite good. I'd look for one of the earlier, all steel, versions. I'm sorry I can't tell you which one would work, but I'm sure your could get one of them to fit.

The alternative would be to have someone modify a base to fit the short tang on the Cadet action and use something like the tang mounted sights from a Winchester or Marlin lever action (or perhaps the one that fits a Remington Model 141 or a Savage 99) or to weld an extension onto the tang and inlet it into your stock.

I'm wrestling with the same question as I consider building a custom rifle on a thick-wall Martini action in .25-35.

I don't know, but I think the Parker-Hale #7 is a fairly sophisticated sight. This one came off my BSA #12 target rifle. Adjustable iris aperture.