Tim Finley's 'Crossover' Article-Optical centre?

[derek austin]

After reading the esteemed Mr F's recent article in the mags, I thought I'd check over my new AA MPR/Lightstream set up.

As per, I optically centred the windage of the scope (90 out of 180 clicks L-R total), and shot at 10 yds, pretty much on it, a tad right. Then tried at 25yds (max in my garden), and shooting a long way off left.

"Aha" me thinks, "time to do this here shimming he mentions". Down to model shop, sheet of brass as per instructions.

Now then, brain starts to hurts a bit - I think that if it's shooting left, then I should pack the shims 'alongside' but 'under' the dovetail of the mount on the right, rear mount?? Unfortunately Mr F doesn't make this clear in his article...

ie should the shim(s) go on the opposite side to the 'misfire' - shooting left, pack on right? - and presumably only on the rear mount, not both?

So, two little bits of shim end up on rear right mount, and POI at 25 yds moves R as required..

Anyhow, having got it shooting straight at 10 and 25, albeit with a bit more help from the windage turret (which really I shouldn't need), I get down the club and my first pot at a 40+ yarder goes a good 2" left (no wind, BTW, and I'm not that bad a shot), necessitating a good old fashioned crank of maybe 10 clicks to the right to bring it straight.

Now I'm totally confused.

(Don't have this problem with my Daystate/Zeiss BTW.)

All help gratefully received.

Derek