Well Ruger brought out their full size Blackhawk with a seven or eight shot 327, I forget which. They said it's just too high a pressure round to put on the SS frame. Some just don't or won't realize the 357, for example, operates in the 30k's. How many people would run a full house 357 in a SS? Yes I'm aware that there is a different back thrush between the two, but I'll bet they are close with the 327 running 49k.The 1889 7.65 Belgian Mauser may have used a lighter load than later 7.65 rounds meant for use in the 95 and 98 type actions, the 1909 rifles have a pretty good rep but a friend showed me one he was rebarrling, one a girlfriend had bought for him for his birthday and she hadn't known enough to inspect the barrel properly. This action had some setback of the locking seats, but not so bad that he couldn't rectify that before cranking on a new barrel.
He used a setup made from a cut off barrel shank bored out to hold the shaft of a diamond coating wheel. He used this setup to blue print actions before rebarreling, in order the smooth the locking recesses so there'd be no mistakes in headspacing and rifles with minimum headspace would close easily.
Theres a limit to how much material can be removed, no more than a couple of thou for most actions, the heat treated layer shouldn't be thinned much if any.
Of course the setback area has its surface setback as well so only metal standing proud of that is removed.
If the 7.62 NATO had remained at its original specifications there'd be no problem with older action types if still in good condition, but the modern run of 7.62 often greatly exceeds the original pressure range of 47000-48000 CUP, and acceptable max std deviation is pretty wide for the heavier bullet loads.
If someone has a 93 or 95 they have shot many max power loads through without problems I'm glad to hear it, but it doesn't gaurantee that every other rifle of that type can stand up to repeated use as well.
I've seen far too many old warhorses still in the original chamberings that show setback to receiver or bolt or both to assume it can't happen with rifles of the same vintage rebarreled for a more intense cartridge.
Now to get back to centerfire conversions.
The .25 ACP sounds interesting, and a long case .25 auto cartridge was developed for extra punch from pocket autos.
Theres a obsolete .22 centerfire cartridge with balistics close to .22 LR. I don't know if cases can be found for those.
These allowed small bore target shooters to build their own loads taylored to their rifles.
There were 6mm and 7mm"VeloDog" cartridges made for small revolvers carried by bicyclists in the old days, when bikes were still called velocipeeds.
Some of these were also used in small game rifles.
I'd thought about having a .25-20 cylinder made along with .25 barrel, but even if the cylinder filled the entire frame opening factory cartridges wouldn't fit, and only deeply seated bullets could be used.
On examining my old model SS I see that the topstrap is pretty substantial, but not 40k+ substantial in my opinion, and even in its .22 WMRF chambering the frame did open up a hair requiring some rectification and a shim provided by a member here. Could be a heat treat issue that resulted in frame spread of my SS.
Theres a lot of steel there but the frames may not all be as strong as the successful conversions posted of or made of as good a steel.
Later production Single Sixes may have benefitted from improvements in metalurgy at Ruger when the more powerful Magnum pistols went into production.
I hadn't been looking for one of these, it just fell in my lap so to speak, but after giving it a lot of thought the .22Mag is plenty enough for any expected use I might put it too.
In the .32 department my little I frame Hand Ejector is good for now.
I like the idea of a .327 revolver so long as the small diameter can be put to use in a cylinder of seven or more shots with no more bulk than a six shot .38 or .357.
PS
I've been thinking about designing and builing a prototype of a low cost home defense revolver that can digest 9mm ammo.
My ideas on this line is for a DA only revolver with simple push pin cylinder removal for loading like the old turn of the 19th century low cost pocket pistols.
Main thing would be to use only the best steel for the frame and cylinder, in order to avoid pressure related accidents should the bore get obstructed with pocket debris.
I've often been asked to clean up old pocket pistols that had been carried in a purse or coat pocket for decades without any care at all.
I've found everything from lost ear bobs to remnants of tootsie rolls stuck in chamber mouths or muzzles.
One old timer had a .25 auto he'd had a leather sleeve made for to keep out pocket debris. I found that a small portion of the stitching had come loose and pocket lint had migrated into the muzzle over the decades till half the bore was plugged by a felt like mass.