Unless you decide that you are going to shoot exclusively with non-glass sights such as iron sights or peep-and-globe target sights, eventually you are going to have to deal with the issue of scopes, including mounting and adjusting them.
For some basic background information, check this blog on mounting scopes — http://188.8.131.52/blog/2009/03/mounting-scope.html — and this blog on adjusting them — http://184.108.40.206/blog/2010/04/how-scopes-really-work-and-what-not-to.html .
At some point, however, whether you encounter a springer that has built-in barrel droop or find yourself with the desire to shoot a pre-charged pneumatic air rifle at really long range, you are likely to run into a problem: lack of sufficient elevation adjustment in your scope.
I have faced that problem several times in my airgunning career, and, to my knowledge, there are only a handful of ways of addressing it. The first is to use a different scope, one that has a greater range of adjustment. This can work fine but is generally the most expensive option.
Another option is to switch to a special “drooper” mount for the scope. Some manufacturers offer special drooper mounts that are designed to work with their airguns that have barrel droop built in. I have used these special mounts successfully but they lack flexibility beyond their built-in droop compensation because they cannot be adjusted.
Alternatively, some airgunners opt to raise the back end of the scope by placing metal or plastic shims between the underside of the scope tube and the top of the rear mount. The danger with shims – especially if you are trying to achieve a large amount of vertical adjustment — is that by raising the scope tube at the rear and providing no compensation at the front mount, you raise the possibility of putting mechanical stress on the scope tube that could bend the tube or damage the scope. I have successfully shimmed scopes in the past, but it is not an optimal solution and doesn’t work well when you need a lot of adjustment.
Another option is to “lap” the scope mount rings to angle the scope downward as it passes through the rings. I have never personally used this method of providing for additional elevation.
Finally, I have in the past seen scope mounts that could be adjusted fore and aft to provide additional elevation adjustment, but most of these (a) looked flimsy to me and (b) required dis-mounting the scope to make adjustments.
But now the good folks from FX airguns have introduced something called “No Limit” mounts. They look like ordinary scope mounts, but there is an extra Allen screw above the foot of the scope mount.
With the scope mounted straight and true, you can loosen those Allen screws and adjust the elevation by lifting the front and rear mounts to different heights. Because the mounts go up and down while tilting forward or back, the scope can maintain a stress-free and relaxing hold. This allows you to optically center the scope without having to custom lap or shim the rings, and it also allows the long range shooter to re-position his scope angle for a better range of adjustment at extreme distance.
With springers with droop in their barrels, the No Limit mounts allow you to customize your scope angle to align with barrel angle. The folks at www.airgunsofarizona.com tell me pcps have different angles too. They see it when moving one test scope from rifle to rifle. No Limit mounts allow the shooter to “tune” the scope to the rifle before cranking on the elevation turret. Even if you don’t have a barrel droop problem or lack of elevation range issue, the No Limit mounts can raise or lower the scope to fine-tune its alignment to your eye.
No Limit mounts do not offer any windage adjustment. The designers at FX felt that if they allowed left/right movement, it would be difficult to keep the mount stable, so they steered clear of that feature.
In my view, FX has come up with an excellent solution to a problem that is bound to vex every airgunner sooner or later.
Til next time, aim true and shoot straight.
– Jock Elliott