I'v seen scopes mounted both way ; over reciever, and foward over bbland reciever.
what is the differance in mounting this way.
which works better,pro's and con's

In my experience the forward mounted scopes are quicker on target and allow you to shoot with both eyes open.

The only real con I can think of right off hand is unless you use a red dot scope you have to use a scout or pistol scope which has a longer eye relief. Those scopes are generally more expensive when compared to a comperable scope with standard eye relief.

All that being said I have a forward mounted scope on my guide gun.

On a hard kicker like the 45-70Marlin I prefer making everything out of steel and having it solidly screwed to the receiver....

Thus my old Weaver K4 on a redfield base with leupold rings.

The ONLY thing that'd make me happier is a dual dovetail Leupold base.

AllanD