Bob,

I use the Gehmann 590 sights on a few of my rifles (HW30S, HW99S, & HW95 SuperMatch).

https://gehmann.com/english/products...2&kategorie=22

The clamping on the 590's is designed for rimfires/PCPs, so is not as 'fierce' as is needed on a 'full-power' springer

I have drilled and tapped the mount body of these sights, to take an M3 bolt to engage in the arrestor holes in the HWs cylinders - works very nicely

The issue with the 'fully milled' Anschutz 6xxx sights, is that the base is split lengthways, so is very difficult to fit an arrestor bolt.

( However, I have an Anschutz 6502 'fully-milled' on my Anschutz 335 Mk2, and so far, touch wood, it has not moved/slipped yet.)

The 'cast' Anschutz sights (e.g. on late model Webley Mk3 SuperTargets) do have a facility for use of an arrestor bolt.

Have fun

Best regards

Russ