Does chrome moly last longer than stainless?
The adi reloading guide gives pressures from 45,000- 60,000 psi for popular centrefire rounds, of course using trail boss for making centrefires subsonic drops the pressure to around 25-27,000 psi.
40,000 psi is 275 Mpa which is the tensile yield strength of 416 stainless, the yield strength is where it starts to go through inelastic deformation before it fails which is the ultimate tensile strength which is 515 Mpa for 416 SS.
Chrome moly has a yield strength of 435 Mpa and a UTS of 670 mpa, if your loads are less than 63,000 psi according to the adi book you are below the yield strength of 4130.
I would go chrome moly over stainless on the fact chrome moly would be below its yield strength for the maximum pressure loads in the adi book with stainless being above the yield strength on start loads.
The saving factor here is these pressures are only sustained for a tiny fraction of a second.
Stainless can handle heat a little better than 4130 which like pressure is not sustained for great durations.
A colour heat chart will show black is the hottest colour for things left in the sun, perhaps stainless has an advantage in cooling when walking around in the sun as it will not absorb heat like a black barrel.
Perhaps the accurate lifetime of a gun is much shorter than its lifetime it could fire,i reckon a 22lr would win this one.