If it's a Woodchucker, it was made from 1988 to 1990 and distributed only by RSR. IIRC, the .22 LR version uses the 2000 action and the .22 Magnum uses the 64. This was a tiny rifle with a 16" barrel.
If either of them are early rifles, you might try BKL rings. They work for most all dovetail widths. Even on newer rifles some rings don't fit well due to the receiver radius.