I saw more ACOGs fail then I did Mk4's. Now... they were standard issue on every rifle, so every cat had one, so numbers probably don't matter. Not an indictment of Trijicon, they make a grunt proof scope, but I don't recall Leupold MK4 failures being an issue. I'm sure some did but if it were systemic, I would have heard about it.
No offense... they were well regarded because dudes didn't know any better. When your only experience is with a 4x Acog mounted on a non floated M16 shooting greentip; a 3-9x Leupold on a MK12 or SDM rifle with 77gr SMK's is worlds better. Just about any optic/gun/ammo combination is better. There is a reason the 8541's weren't using Leupolds....
Leupold Mark 4 variables have the highest failure rates of any US mil issued sniper optic. Roughly 20 times higher than Nightforce and twice as high as the PSR S&B's. Those are/were the numbers returned to Crane. That's outright failures- not including all the scopes that track and adjust incorrectly, lose zero, failure to return to zero, etc, etc. I've seen hundreds of Mark 4's tested. Fully 30% have major problems out of the box, of the ones that work "ok" the vast majority will have a zero shift, tracking errors, or failure to return to zero within 400-500 rounds.
Here's one simple reason why you didn't see or hear of problems- you never pulled the same Lot of ammo from range trip to range trip. Why is that the first thing done on a live fire range is to zero, even when an individual zeroed his rifle two weeks before? Different lot numbers and zero shift.
