Does anyone make a riser for a flattop that will return to zero when removed want to be able switch between my aimpoint and a conv.scope thanks....Doug

ARMS #38 will be my choice if it works with your scope [img]armsmounts.com/images/prod_38.gif[/img]

I bought a #38 but the BUIS won't clear the objective of my SN3, so I went with a #37 instead.
[img]home.earthlink.net/~whitman/CLOSEUP.JPG[/img]

There are two basic ways to go. You can put a riser on and leave it there and use the apropriate ht. rings such as the 22M68 aimpoint ring without spacer, and #22med. ht; throw lever rings. On and off with a platform that should be semi perminent is not a good idea as it could be a problem with repeating zero as you astutely point out.
The second way is to use like the 22M68 with a full spacer direct off the receiver, and the conventional scope via high rings. The problem can arise depending on the conventional magnified optic is that the flat top may not be long enough as you most likely have discovered with certain optics. The ARMS #36 ex OSR  (optical sight rail) or #38 ex would prob be two of your best bets with the correct ht. rings.
Good shootin, Jack