Re: Question about a H&R single barrel 12ga
There have been countless deer taken with that exact same shotgun, shooting Fosters type slugs. They can and will shoot fine and sometimes they can actually be quite accurate. As far as having it drilled and tapped but there isn't a hole lot of material there for a mount that can handle a larger scope. A small, short, lower power scope or red dot type sight should work fine. Good luck.
Big Al's "Take-Em" Style Silhouette Decoys Pro-Staff.