I have come across a shooter M61 that I have a question on. I only gave a short peak at is as I had to run for an appointment. It is not grooved but does have two sets of holes D&T'd, one set on the receiver and one set on the barrel. My short bit of research indicates that the holes were added. I have also found that Weaver made bases for the M61 #19 rear and #13 front. I am going to head back tomorrow to look at the gun more closely but it would be great to understand the scope mount situation. Any help is appreciated.

That is the suggested Weaver base mounting location, but I have an early 61 and I was not about to have the barrel drilled and tapped. Looking at that receiver and the turret location of the 2-7 Leupold Rimfire that was going on it, I saw no reason that the rear Weaver mount wouldn’t work just as well up on the front of the receiver. My gunsmith thought the same thing and drilled and tapped the receiver for two of those Weaver rear bases. It came out perfectly.

Great. Just what I needed to know.

Yes, too late on that one that you are looking at, but scoped I think that mine looks cleaner than even the later and more expensive grooved 61’s.