spaniel

First you make sure you mount the scope at the correct distance from where your eye is when you mount the gun in shooting position. You can tell it is correct when there is no dark floating circle visible and you see the full width of vision in the scope as light with sharp edges around. If you see the dark circle it's too far away.

Then, pointing the gun at the sky you focus the eyepiece so the crosshairs are nice and crisp.

Does your Buckmaster have a side focus knob? Cheaper scopes or those made for shorter-range shooting (ie rimfire scopes) have "fixed parallex", meaning that the scope is set so that at 100 yds if your eye is off center through the scope it won't matter, the point of impact will still be the same. If you have side focus, you need to adjust this for each range you shoot at. This may seem like a bother but it increases your accuracy. Roughly, you can set it by using the side focus (or some scopes have this on the objective lense) to bring the target into crisp clarity. If you have it right, with the gun ridgedly held still you can move your eye left to right if the centerline and the crosshairs will not move on the target. If they do, you don't have it right.

The easy way is to always make sure you are looking right down the center of the scope -- the above paragraph is less important if you are good at that.

Whether you can go back to open sights depends on if your rifle can even have them mounted. Seems most rifles sold today are not dovetailed/drilled for open sights.