Dovetail slot too big ?

Last year I came across an Anschutz/CIL Model 125 .22 for sale in very good condition for $100. I bought it. Only problem was that it was missing the front and rear sights so I just slapped a small rimfire scope on it seeing as I already have a couple for hunting. It turned out to be very acurate, as I expected being made on the anschutz model 184 action. I decided to finally pick up a couple sights for it but my front dovetail slot measures the normal 3/8" and the back is 7/8", way too big for any rear sight i have ever seen. It doesnt look to be filed out or tampered with. Anyone see this before or heard of different size sights than 3/8"?

Thanks
Labrador