I recently acquired a Remington 512 “Sportmaster”. There are some holes tapped in the left side of the receiver. I believe these are for a scope-mount. Does anyone know what type of scope-mount would fit this rifle and where I might be able to get one?

A Weaver #2 side mount should work and Weaver is a popular brand.
http://www.weaver-mounts.com/charts/charts.aspx

Brownells lists it.
http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=19023&title=SIDE+MOUNT+1%22+RINGS+%26+BASES+-+R-Z

Bye
Jack

The #2 Weaver QD Side mount base uses 4 screws to secure -- the outer two are 2 7/8" OC and the inner two are 2 1/8" OC. I'm using that mount on a Rem 513T which, I believe, uses the same receiver. Works well.

Bud W