The mount is fitted to the right-hand side of the action, but the offset to the bore is very slight. Most get used to it very quickly - remembering that only the USMC 03 sniper, with its x8 Unertl scope, had an over-bore scope LOS.
This is a quote from Latigo St Marie of Swiss Products, who actually makes the things...'The offset is .675". If you can tell that difference at 100, 200 or 1000 yards you're a much better shot than I am, Gunga Dihn!
The offset on the SP mount is less than the offset on the M1D Garand sniper rifle. Zero it at 200 yards and then see if you can factually shoot a group of 5 or 10 rounds and tell the difference at 100 or 500 yards. None of us do that.'
I've had the alloy version for a number of years, as well as both the early and the new versions of dioptre sights - all do exactly as they are meant to - perfectly. Some folks finagle a piece of bent alloy to deflect the spent case away from the scope tube - coming from a long line of professional 'Red Greens', I use duct tape, and perform the extraction with an element of gentlemanly finesse, rather than try and see how high and far I can fling the empty case...
I note that Zedbra has a side turret on his spiffy Zeiss scope - right in the path of an extracting case. Well, I just have a K4 Weaver on my K31 - more in keeping with the spirit of the arm, and compusly anyhow hereabouts, where vintage 'sniping' comps are limited to a x4 power scope of any kind, to give those poor buggers with No4[T] rifles some kind of a chance, I'd guess.
tac
