I have had a couple Mk-I's still have several Mk-II's and One MK-III (sold it to a buddy)it was a blue 6 7/8 GTM-- I had a 2x Nikon on mine-- shot very well even with the cheep ammo and pretty much one hole with the good stuff-- You should not have any trouble getting under 1" @ 50 yds.

I removed the loaded chamber indicator from mine-- just kept getting gumed up and collected dirt.

I have had several with scopes most all would do an 1" or so but the GTM MK-III was by far the best shooter I had.

You should have fun with it--good luck