I’m no gunsmith, but my wife’s schuetzen rifle is an 044 1/2 in 28-30 120. I would think a 25-35 with a .422 head size wouldn’t leave much meat in the barrel shank. Don’t think I would try it.
Mike

The action will handle moderate loads of a 25-35, but it’s kind of a pointless endeavor.

All you will really be able to shoot is about 90 grain or less bullets, and if they are lead, not much faster than you could with the 25-20. The twist rate is just too slow. But you might verify what it is.

Then because of the size of the barrel and overall weight of the rifle, it can be tough to control with heavy recoil. If it’s not a tapered barrel, that would be a plus. A bit wore weight and less flexing under a heavy load.

256 Winchester magnum (357 necked down) or 25 Copperhead, 222 rimmed necked up, might be a better choices if you want more available brass and a bit more speed.

There is enough interest in the O44 1/2 rifles it would be a shame to ruin a nice one. I’m always looking for nice or different ones I feel you decide to sell, keep me in mind.

Jeff_Schultz wrote on Oct 9^th, 2022 at 5:53pm:

For the same reason that dog's lay in the road and lick their nuts. Because they can

It all depends on what you want to use the rifle for. I would have a new barrel made so the original barrel could be left alone to preserve the collector interest. Because of the 3/4” diameter barrel shank, .28-30 would be a good choice along with  possibly .357 mag, .32-20, .25-20 wcf, .218 bee, and .22 hornet.
You might be better off trading for a 44 1/2 or another rifle.

I would just send the action to CPA and tell Gail what you want for a caliber and she will we barrel it. You would still have the interchangeable barrel 25-20 if you ever want to go back. 
I have several 44-1/2 with interchangeable barrels. 
That little 25 is a great caliber.

Agree that the .25-20 ss is a great caliber. Remember that this rifle is not a 44 1/2, it’s an English model 044 1/2 with a smaller frame and barrel shank size, which really limits the cartridge case size or diameter to be safe.

What do you want to use the rifle for and why do you need a more powerful cartridge??  I’d have to ask myself those questions.  I have a 0441/2 that started out as a 25 rimfire.  Gail at CPA was a tremendous help in understanding this action and the limitations of the barrel shank.  She set me up with a 17 HMR barrel.  Not exactly my first choice but options are limited with rimfires and I found it next to impossible locating a centerfire breech for my rifle.  My next, and likely last, barrel will be a 22 mag.  Talk to Gail and consider sticking with your current chambering.  Think of it as a legacy to the bygone days of target shooting when Stevens made a good trade in selling these rifles.  And that’s historically interesting.  And that makes the rifle and cartridge interesting to shoot!

PS - if you decide to sell I’d appreciate getting the opportunity to see what you have.  Let me know!