Howdy
Sheesh! The Colt SAA and it's replicas are large framed revolvers. Just for the fun of it, I just grabbed one of my S&W Model 28s and a Colt SAA. The cylinders are very similar in size. We tend to forget that just because they are not as big as the 'original model' Vaqueros, the SAA is still a big gun.
The Colt Single Action Army was first offered chambered for 357 Magnum way back in the 1930s when the cartridge was first introduced. This ain't nothing new. There is plenty of steel in the cylinder of a SAA or any clone of it to stand up to a steady diet of factory 357 Magnum loads. No, you do not have baby it with 'moderate loads', although you may not like the recoil and muzzle blast of a steady diet of 357 Magnum loads.
Same with the Ruger New Vaquero chambered in 357 Mag. Although the chamber walls are relatively thin when chambered for 45 Colt, the much smaller holes of a 357 Mag leave plenty of steel in the cylinder. The New Vaquero is a stout gun and can take a steady diet of any SAAMI spec 357 Mag ammo you care to feed it.