I've had early, pre-BTR Athlon Cronus scopes on both the Jelrod-converted 40X/XB rifles, and liked them fine, so went with Cronus BTRs on my two competition V22s. Once I got used to the thinner reticles - particularly the thinner + aiming point while shooting movers - I've been very pleased with both these scopes. They track perfectly, and the optical quality is very good. I have a minor issue with how stiff the parallax knob is, especially in cool weather. This wouldn't be an issue at all if these scopes had the depth of field my Kahles K624i scopes do, but the Cronus are pretty dependent on correct parallax settings, which slows me down a bit when shooting a stage with targets at a wide range of distances. Still, in this price range, I doubt you'll find a better scope. I'd like to play with one of the newer Kahles K525i scopes, since they'll focus down quite a bit closer than my 624s will. Since the K525i has a much shorter body than the K624i, I'm not sure that it has the same depth of field that the 624s enjoy. But given how well the Cronus scopes have worked for me, and the fact that I can buy two Cronus scopes for the price of one K525i.....I'm not at all sure that the price difference is worth it.
Pro Series Parallax Adjustment Wheel
Upgrade your optic with one of our Pro Series Parallax Adjustment Wheel, speeding up parallax adjustment without breaking the bank. Our parallax adjustment wheels are proudly printed in the USA from durable custom made Nylon polymer, They install in a minute or less, and come with a lifetime...
mkmachining.com
Best upgrade I didn't know about. Really helps with fine tuning in addition to making it much easier to manipulate.