I recently received a left-handed Remington Model 700 SPS Varmint in .308. I mounted a Brownell's steel Picatinny base, Brownell's Picatinny rings, and a Nikon Monarch 6-24x50 scope. I tried to rough in the zero using a Sitelite 100, and found the scope was looking at a point way above and to the left of the bore line. The knobs maxxed out long before I had any sort of a zero. I had decided to follow the shoot one/clean process for the first five rounds, and couldn't get a round on the large target at 100 yards. I took the scope and rings off, and completely loosened the two rear base screws. With the two front base screws torqued down, I can slide a .020" feeler gauge between the rear of the base and the top of the receiver easily. I am thinking I need to cut a piece of shim stock to fill this space, or use bedding compound to build up the rear of the receiver, but this is uncharted territory for me so I would sure appreciate any guidance! I am obviously not a smith, but I am pretty handy in my reasonably well equipped garage! Thanks in advance for any help or condolences!