No ...But have toyed with the idea of a shorter rimmed version on a 357 mag case.
The 1-200 thou free bore section worries me if it would be easy to get to shoot or not.
Breach seated maybe a pain.
I’d like to know too.

I barreled a BSA martini to 300 Blackout but with a rim, I use 360 Dan Wesson Brass . Makes a fun plinker.
I use 180 gr. plain base bullet with good results.
Dales

Tough question to answer for a single shot. Most data and shooters experience  will be AR 15, short barrel based, with velocity below 1100 and above 1700.

When you go to something hand fed the options of powder/bullet combinations probably triple at least.

I have shot everything from 80-265 grains. The 80 grain top out over 3000 fps in a barrel over 18” long, the 265 around 1400 in something as short as 12”. Everything can be shot at 900 fps. Depending on powder choice.

Twist rates from 1/5-11 will stabilize cast as heavy as 200 grains. 1/9 or 1/10 is very versatile.

It can be a very versatile cartridge in a single shot.

The other thing to consider would be brass. Will you be using a rimmed case or rimless. The rimless cases will stand up to heavy loads, something using most of the pistol rimmed cases won’t hold up to 50,000 psi if you go there. Using 222R or magnum rimmed solves that.

The cartridge is kind of a can of worms, best to decide what you want to do or since you have the barrel already, figure out what the parameters for it will be. The real limit will be how long of a bullet can be shot at how slow of velocity of that twist. MOA or better is obtainable across a broad choice of bullets and velocity. 

The only thing to add would be other than sight radius, there is nothing to be gained in a barrel over 22”. And some of the heavier slower bullets start losing velocity at 24”

Something I forgot about, the case capacity basically gives you you a 30-25 depending on the grade of black powder you use. So you get better velocity than a 32-20 and a better selection of bullets.

Never tried to breech seat it, but......

want a challenge? 30 Carbine.

Aaron

Rebel wrote on Jan 2^nd, 2021 at 8:27am:


That surely would be a challenge! 

The 30 carbine round has basically disappeared from out here in Aus due to our overly policed and regulated firearms legislation. It would be easier to find .461 Gibbs cases than 30 carbine...lol 

Go ahead and build it. but I think you'll eventually get tired of it.  Like the once-vaunted .30 Herrett, it's a cartridge with a narrow range of utility.