I am considering purchasing a Mark XIX and want some opinions.  I want to add this pistol to my collection because I like the concept of the gas operation and appreciate the magnum calibers.  I would use the pistol mainly for fun target shooting, but may want to hunt with it (basically I will probably never put more than 1-2K round through it).  I have shot one in .44mag and really liked it, but would like to know a little more about these before I purchased one.  I think I remember reading in a post some time back that these had problems with the gas piston (or maybe piston rings?) wearing over time.  I have also heard about frames cracking with the .50AE.  I would like to know if there is any truth to what I heard or if anyone else has opinions about this gun.

btt

Thank you Tyler Durden, that is the info I am after.  I wanted to hear something from someone who actually ownes one and is not a range that rents them & sells them.  By the way fight club was a great movie!

I own two.
A MK7 .44 with a 6 and a 10 inch barrel with a 2.5-8 power Weaver on top.
several thousand rounds through it and no problems.
Best group=3 rounds @ 100 yds in .908 of an inch.  (Yes,Yes--Off of a solid rest)
Took my deer last season with it.
One shot-dropped it like a festering hooker.

The other, a MK19, polished blued with 24c. appointments in .50AE.

I've never experienced a more controlable stick of dynomite in my life!  This thing is a frigging CANNON.  No problems yet other than finding recipies (any suggestions?)  I'll stick with the 6 inch barrel on this one and no scope.  I've only done short range work with it so far but 0.937 at 25 yards is respectable with this powerhouse.  It's HEAVY, I'm light, I don't care!  I passed this thing off to a kid @ the range.  Must have been around 100 lbs, mabey 15 or 16 yrs old.  One shot, he hit paper, the whites of his eyes looked like a whitewall tire on a Modle "T".  When he could finally stutter, all he said was "I want one of these when I get older!"

The kick is harder BUT MORE CONTROLABLE than a 454 CussYouAll.
One warning !!!!!!!!!!!!!
Don't get out of practice.  Experience is all that keeps these cannons in your hand after 20 or 30 rounds in one setting.