The Trooper Mark III and Trooper Mark V were extremely strong revolvers.
Master gunsmith Jerry Kuhnhausen thought they were the strongest medium frame DA revolvers ever made.
They were expressly designed for unlimited shooting with factory .357 Magnum ammo.
The only possible weakness is that you need to use snap caps to dry fire or risk a broken firing pin.
Firing pin replacement in these models requires a trip back to Colt for replacement, or risk damaging the frame.
Later, Colt fitted the Mark V with a full lug barrel and made it in stainless steel. At that time they changed the name from Trooper Mark V to the King Cobra.