What to look out for

If you’re shopping online and trying to navigate the minefield of scope rings, this page should help simplify the process. While it's usually best to try hand-fitting components, I know that's not always an option these days. 
If your only possibility is going by the numbers, these numbers should be a useful reference.

The measurements you should be aware of:

Most scopes nowadays attach to a rail - picatinny and weaver being the most common two. Picatinny refers to a standard width and tooth spacing style. The length of the rail can vary, so make sure your rail is long enough to fit both rings onto its length (or a split rail spaced far enough apart for both rings to fit).

The objective bell is the wide end of the scope - the one where you don’t put your eye. It’s the bit that faces the target, and also contains the objective lens - hence the name. This is the main part we're trying to keep from touching the rifle. Often, shooters try to get the objective bell as close to the barrel as possible without touching. The legend goes that if you can slide a dollar bill between the bell and the barrel, well then... they're not touching.
The objective bell is measured across its diameter, and is typically listed in mm. 

The scope tube is the part the rings hold on to. It’s the main round tube-looking section of the scope, potentially bulging in the middle due to the turret block. We generally tighten the rings on to the scope tube with 15 in-lbs of torque. The size of a scope tube is the diameter, often listed in precise mm values.

Straight-tube scopes with no discernible bell will need to be lifted enough for the turret block or eyepiece to clear the rail. Neither the objective bell nor the turret block should at any point be touching the barrel, receiver, or rail.

The Chart

This chart is meant for scopes where the objective bell is wider than the scope tube. Some scopes (such as our M82G2) have no bell, and measurements such as eyepiece size are used instead.

This chart provides the height difference that the rings (and rail) need to 'make up' to clear the objective bell. 

• If your objective bell is going to sit completely over the rail, this chart will refer directly to the ring height needed to keep the bell from hitting the rail.
• If your objective bell hangs partway over the end of the rail, you will need to check the actual angle and placements of the bell to know if you clear the rail (see photo at top of article for example of this situation)
• if your objective bell completely clears the rail (or only partway), this chart will refer to the height of the rings plus the rail. Subtract the height of your current rail from the values on this chart to get the ring height remaining.
• If the clearance is little enough, the chart will list Turret Block to let you know to check that measurement too.

This chart is an absolute minimum. Please add a small margin (1/16") for manufacturing tolerance, rail placement.