There is another factor involved called hoop stress.

What it boils down to is the larger diameter the chamber is, the more metal it takes to hold the pressure.

Look at it this way.....the chamber walls at the thinest point are about as thick as the walls of a 55 gallon steel drum, but you can be well assured that a 55 gallon steel drum won't hild 1/10 the pressure of a 44 Special load.

It is wise to keep the loads in a 696 at 25K or less. If you do that, it will hold up about as well as the L frame .357 Mg. at 35K.