Are Ar's harder on scopes? I built a lightweight with a 16" bhw barrel and a Midwest keymod rail and I've had 3 scopes fail on it in a year. It'll be shooting great and then a flyer or two and then groups go to crap then I loose zero all together. It is a carbine length gas system but it is completely reliable with all the loads I've tried. Other than eating scopes.
I've never had a scope fail on an AR and most of mine have been carbine gassed. But I don't use $20 scopes either, Leupold and Trijicon have worked fine for me even with H2 buffers.
Somewhat of a double recoil in that the mass of the carrier group creates a mini recoil slamming home. Somewhat like an air rifle can destroy a good scope.
It generally doens't happen often.
I've had it happen to one Leupold, and a buddy had it happen to 2 Leupolds.
I have a cheap Pentax on one of mine right now... long story there, but the pentax is becoming blurry and the scope only has maybe 500 or so rounds in it, holding zero fine so far but that will be next to go.
Generally speaking its not an issue. But it does happen.
OTOH who is to say the couple I"m aware of, wouldn't have had issues on a bolt gun, it does happen.
But the carrier mass has to be about the heaviest forward motion of any gun I can think of right off the top of my head, though I"m subject to be wrong about that.
This was 20 inch rifle uppers only.
We can keep Larry Root and all his idiotic blabber and user names on here, but we can't get Ralph back..... Whiskey Tango Foxtrot, over....
Cheap scopes will let you down sooner than later no matter what they are on. I've had pretty good luck with the Bushnell AR scopes on lower end (~$150). A AR15 isn't uniquely hard on scopes.
"Life is tough, even tougher if your stupid" John Wayne
There's something else going on here. Millions of guys have scopes mounted on their AR's with all different gas systems and having a scope fail is a very rare occurance - having 3 scopes fail tells me something else is going on.
I just put a sightron s2 4.5-14x50 on it while I wait for a 30 mm mount for an SS. I have a 10x SS on my 6.5 grendal and it has been fine so far. I was trying for a little less weight on the 5.56.