A level scope is vital for precision shooting as it ensures that any windage or elevation adjustments made actually work the way they’re supposed to. In fact, it’s more important that the scope be level with the horizon than the rifle itself be level. Most shooters level the scope body to the rifle itself as a quick “good-enough” method.
Several products on the market today can help you level a scope body to the base, but what if you don’t have them around? One common method is a set of feeler gauges available at any hardware store. But there’s an even easier and cheaper way to do it that you might have tucked away in a drawer: a deck of cards.
I first heard of this trick years ago from Frank Galli, an author and owner of Sniper’s Hide. Mount your rings to the base and place the optic in the desired spot. Tighten down the rings enough so that you can still slightly rotate the scope in place. Then take a small stack of playing cards (or business cards) and insert them into the open space between the flat bottom of the scope and a flat surface below like the bottom of a one-piece mount or the top of a scope rail. Add one card at a time, gently rotating the scope side to side as needed until you can’t wedge one under any further. Now carefully remove the stack and tighten down the optic. All done.
Of course, this assumes you have a flat surface below and the mount itself is square to the bore, which isn’t always true. In both cases, we’ll turn to the plumb line technique as a final check, but that’s a tip for another day.
