The Trooper Mk3 is a first rate revolver. Jerry Kunhausen's opinion is that the Colt Trooper Mk3 and King Cobra series guns may well be the strongest medium frame revolvers of all.
They have little to no timing problems. I've owned a number of them in .357 and .22LR, and I've always been pleased with them.
Comparing the "cheaper" Mk3 blue job to todays guns is an eye-opener. They have a beautiful, deep, glossy blue finish.
The only possible weakness of these guns is a few may have firing pins that are too hard. If you dry fire a lot, one MIGHT break. if so, the gun MUST be sent in to Colt for pin replacement. This is NOT a home do-able job.
Other than that, I've never had a problem with any of mine.