My bad. I take a rifle and look at the scope. The front lens is on a sleeve and the sleeve is inside the outer "lock" ring, there are 2 notches on the lens sleeve at the front that I turned the sleeve when the lock ring is loose. No need to completely remove the front lens. LoonWulf is correct! It has been at least 10 yrs!Now my memory is coming back on it. Will need to remove the front lens completely and move the internal thread tube so to lock the front lens at the new setting after adjustment. I remember is moving the front lens forward, so it is possible not removing the lens completely but put an thin O ring at the "gap", turn and seal the front lens. Why I did not think of doing so at the time!
Ah but the BCG does slam forward on a AR15OP, just get a BSA air rifle scope or something like the Leepers Bug Buster. I am not into putting $1,000 scopes on air rifles, especially a break barrel that will have questionable accuracy and will sooner or later possibly destroy it.
I would not put a Leupold on a magnum break barrel rifle unless I was wanting to test their warranty terms and they are not BB guns. The recoil cycle on even medium power break barrel rifles is brutal on scopes and a magnum break barrel will destroy scopes and the more expensive they are the more the magnum break barrel will relish ruining them.
And there is nothing about an AR15 that causes a violent recoil reversal as occurs in a break barrel (springer) rifle. It is not a good comparison or test.
Precharged pneumatic rifles and pumper pneumatics have virtually no recoil and what little there is will be normal in direction. Powder burners may kick seemingly like a mule but while it may seem to knock the slobber out of us it is nonetheless progressive. The instantaneous slamming stop of the spring piston assembly is violent and sudden t hough the total intensity is less there is a damaging spike and it is in the wrong direction to make it worse.
Ah but the BCG does slam forward on a AR15
my experience is disagrees with yours .i am not some one that go's out and bangs out round after round . i ws just setting a bench working up loadings to find that loading that works very well.Not even close. I too have an AR and enjoy it and they can be rough on scopes when we start banging away with them. People often put more rounds through an AR in one session than through a bolt rifle in a lifetime. Thats what gets the scopes on ARs, not the bolt closing.