They are very durable and will maintain zero no matter what. In fact, you have to thump on the side of the scope when making adjustments just to get the turrets or "reticle" to properly seat into the new adjustment spot. Believe it or not it's in the owners manual and if you don't do this you will have a very hard time zeroing the weapon. All that said, I wouldn't suggest you buy one. At least not without looking at one on a gun similar so you can get a feel for the severe lack of eye relief. Trijicon ACOG's suffer badly for eye relief. Ever wonder why all those evening news clips of soldiers in the middle east are going into a building with the buttstock up on top of their shoulder and M-4 pulled way back and kinda sideways. It aint to look like theys from the hood...it's because you cant see thru the 1400 dollar scope unless you have your eye 1 to 1 1/2 inches from the eyepiece!!!! And that's a shame too because they are high quality and the reticle configuration of the RCO model works very well. I just cant get past the lack of eye relief to the point that it is uncomfortable to shoot coupled with that price tag. All B.S. aside...dude, buy something else, you'll be glad you did. Suggest you look at the Vortex Viper. I do think it was great that it had a Christian biblical chapter and verse notation on the side of it while being used to waste muslims.