I had a .30-06 that was double-grouping. Long time ago.
The cause was an Ocular lens that would wobble, and as it wobbled, the cross-hairs moved with it. I was highly disappointed, the scope was worth every bit of $35.00, and no, it wasn't a Leupold. I can't remember the brand for certain, but it was something along the lines of a bubble-pack Bushnell
I bit the bullet and bought a Tasco World Class($89.00!!), and was surprised at how well the rifle did shoot. The issue that surfaced after that was the fact that eye relief was only about a half-inch, so I got bit e'ry now and then.
Though both scope and mounts were tight, it turned out to be an internal issue with the scope.
I also have a .45-70 Marlin Guide Gun, and it will group very good with a load it likes, and I just plain can't shoot the real hard kickers all that well by the 4th shot.
