They cycle smoother, they are less susceptible to galling, and 4140 is stronger.
Meaning no disrespect, Chuck, you're a good and knowledgable guy:
Smoothness of cycling will be purely a function of tolerances and surface finish. Any other contention is an old wives tale.
Galling was dealt with earlier in the thread.
As for strength, even if 4140 is "stronger", the stainless is clearly more than strong enough (Sakos in 375, Rugers in 416 etc) and has similar endurance limits to non-stainless steel. When you're talking strength, enough is enough, and more is a waste. If the water is 100 feet deep or 1000, you're still gonna drown.
They're either using cromoly from tribal legends/appeals to ancient knowledge touting the superiority of cromoly for bolts or because it's easier to machine.
I'm betting easier to machine.




















































