Here's my favorite S&W 45 Colt revolver:
It is extremely solid and accurate, well made to PC standards. According to SCSW, there are about 50 of these in the country. It has an integral scope mount and barrel weight system on the slab barrel, factory porting, the trigger is first rate, perfectly crisp, with an overtravel adjustment, and the lockup is enhanced with an extra ball detent type lock at the crane/ forward frame. To say it is tight is an understatement. Favorite loads are based on the Hornady 250 XTP-HP or RCBS 45-270-SAA with charges giving velocities in the 950-1100fps range. Power Pistol is a favorite powder, but 4227 and 2400 also do well. I also like Lil'Gun because of it's high velocties relative to pressure, but have heard of some erosion issues with it so have backed off using it in my S&Ws. It will routinely give me 1-1.5" groups at 50 yds with any decent load, sometimes better with favorites. At 100yds it often produces <2.5" groups with the 1 moa dot holosight. I don't know what the cylinder mouths measure, but based on empirical observation of its performance with .452" bullets I'd say they are pretty ideal. I do carry it hunting occasionally with the holosight, but it spends more time on the range with 950 fps loads.
I also have a 4" 25-5 with pinned barrel, and yes it has big cylinder throats around .456+". It does OK with the Rem .455" LRN swaged bullets. Like many of these pinned barrel models, the barrel's forcing cone seems to large for a proper cylinder/barrel relation. It's kinda cool as a revolver though, and shoots well enough. But it is the one I would sell or trade first.
I also have a 25-13 Mountain Gun. Even though it has the dreaded IL, it is well finished and fitted, and the cylinder throats are correct. It also likes the 45-270-SAA (what 45 Colt doesn't?) and delivers about 2" groups at 25 yds when they are driven around 900-950fps. Oddly enough, it also likes the 230 gr Speer LRN loaded to around 930fps with 11.5gr of WSF (my Vaqueros like that one also). It's a fun plinking and short (25yd) range load.