I have a Beeman R1 with a globe front sight on it that is just too small for my old eyes.
A fiber optic front sight would sure be nice! The barrel is 0.625 inches in diameter
and has a dovetail milled into it parallel to the bore that measures 0.332 inches that the
globe sight clamps onto. The dovetail is similar to the one on the rear of the receiver used
for scope mounting.
I am brand new to air guns and would appreciate any advice you folks might be able