Originally Posted by
gloob
I've managed to grind a piece of 20-25 bandsaw blade to fit the slots. Slight turn out to shorten the focal/parallax distance. On really large objective (long wrench), you may need to fold a piece of sheet metal over the spine to reinforce it against bending.
I wonder if there an easier way to turn the objective? Foam rubber pressed directly against the lens, or something? You wouldn't even need to remove the decorative endcap, possibly. Do gunsmiths ever do this enough there are special tools available? Most rifle shooting, you wouldn't want to do this. 100 yards is the magic number where focus is still crisp for most peoples' eye all the way to infinity, at least with reasonable magnification. And you can just buy an AO scope. Or you can buy cheap 22 or crossbow scopes set for 50 yards.
For airgun shooters, a lot of the AO scopes only adjust down to 12-15ish yards, despite what the markings say, and a slight tweak could bring the adjustable range a bit closer for indoor shooting and close range pesting. The factory yardage markers don't seem to be reliable enough to care about, anyway. The Leapers/UTG Bugbuster is a name you will hear a lot, with airgun shooters. It adjusts down to 5, at least, out of the box. The markings claim 3 yards. And it has mildots, which is very useful to manage the sight-bore-offset at very close range and pellet drop out farther.
edit:
"Makes sense at least that the objective lens isn't sealed to the rest of the "guts", as older parallax adjustable scopes would then be subject to failure on a routine basis as rotating seals degraded and yet they don't seem to be prone to doing that (in my limited experience)."
Humm... I examined my sidewheel AO scope. And the objective DOESN'T appear to move when I adjust it!? I suppose the middle lens moves, instead. The end result is the same. The wheel clearly adjusts the focal distance in the exact same way as my scopes where you turn the objective ring. This particular sidewheel scope is a FFP, and I don't understand scopes enough to know if this makes a difference in how parallax adjustment works. Perhaps sidewheel scopes may be better as far as keeping in the nitrogen?
Oh, I have another sidewheel that is SFP. Also can't perceive any movement of the objective when I turn it.