I know of a handi rifle that was a 45 Colt and the owner reamed it to 460 S&W, with 200 gr. Bullets he got a little over 2900 fps with loads worked up with quickload computer program.
Another friend had a 32" barreled H&R Buffalo Classic and reamed it to 45-120 and loaded 40 cal. Bullets in a 45 X 40 cal. Sabot for a muzzleloader . He got 3000 + fps with light bullets.
Not sure it would be worth the bother gain a few hundred fps ?
Im in OH also and if I had a spot to hunt where a 200 + yard shot was possible I would sight my flattest shooting legal rifle at 200 yards and work with a range finder to find the real trajectory your rifle has. If you had a 100 - 125 yard shot you would have to hold quite a bit low but if you had the time to " range " your deer and had a solid rest you could snipe deer at long range if you had the right bullet that expanded at that remaining velocity. A flat nosed cast works good even at low velocities but has a bad BC for long range, a pointed J bullet will shoot flatter but might not expand at 250 yard velocity ?
straight walled cartridges and long range hunting is a tough nut to crack.
Way back when, in the 1940's and 50's, wildcatters led by John Lachuk, John Wooters, Major Nonte, and others developed the proto 444. They took a .303 British or .30-40 Krag case, blew it out to a straight wall and loaded .429 bullets. The .444 Marlin, as developed by Remington is the ballistic twin to this old wildcat. I understand the Australians use a similar wildcat because Lee-Enfield actions are plentiful there, so it's an easy conversion. There's also stories of Lachuk making wildcat .44 Magnum brass from .303 Enfield cases cut down to 1.29", custom chambered in revolvers years before S&W and Remington made the .44 Mag a SAAMI cartridge. I think, don't quote me on this, The American Rifleman ran some articles by Lachuk on his work with the proto .44 Mag in the 1940's.
Ballistic experimenters tried most everything decades ago. What's old is new again.
I think the sweet spot for velocity lies between 357 and 40 cal. in straight case. The problem is bullets for long range accuracy. I know a guy who has #1 in 460s&w. It's a tack driver out to 150yds then it wanders groups considerably. It doesn't shoot any better than my #3s with 200gr sierra bullets. The older xx/xx cartridges have case capacity that is not needed with modern powder. So if you are going to make up a special rifle they would be the first dropped from the list. One I don't hear much about is 445 Super Mag. I had a DW revolver in 445 Super Mag for a short time, didn't like it much and offed it. Pic is from left to right: 410/ 444 shotgun slug, 44mg, 445, 375w with 270 Siver tip, 45/70, 45/90 with 500 cast and a factory 405 win.Attachment 773671
357 max is same boat as 460, vel not problem long range accuracy with hot loads and blunt bullets are. I don't know much about 445 I only owned it a few months but it is close to 460. I also had 500S&W for a short time another disappointment. The point of my rifle is to cover average shots and be practical to take long range shots with practical hold over.
357 Max seems like an obvious choice for downing deer within 175 yards or so.
I have shot gummy tips in 45/70 and am not impressed. My old 1895 will shoot average 1.25" at 100yds with 300gr Hornady JHPs shooting off bench with scope. I shot 2 plus boxes of gummies and group opened to almost 2". Locals love them and think they are atomic deer killers. They are stand shooting deer at 40-50 yds most with TC or Marlin 95 guide series. Any 45/70 bullet will kill a deer and gummy tip don't mean squat except to keep tip of primer in tube. when you get into 38 cal and above the ratio of weight to bore diameter to make a target accuracy bullet is near impossible without increasing the weight which is going to decrease velocity.
Me & Bro have been debating center drill base of 375H&H spitzer bullets to remove weight and plugging hole with Alumilum rod stock. We haven't done it yet because we don't know what effect that would have like Expansion of bullet diameter that could increase pressure. We have nose drilled and filled HP with wax and that didn't shoot as well as 200 or 220 FN bullets.