To calculate if your BUIS will fit under your scope, you need the following information. The height of the BUIS when folded, the diameter of the eyepiece of your scope, and the centerline height of your scope mount. Please refer to our Scope Mount centerline height chart below.
First, take the eyepiece diameter and divide it by 2. Next, subtract this from your scope mounts centerline height. This will give you the gap under the scopes eyepiece, which will determine if your BUIS will fit under it. This can also be done to determine if scopes with a large ocular lens will clear the rail or barrel on your rifle. Take the diameter of the ocular lens and divide it by 2. Next, subtract this from your scope mounts centerline height. This will give you the gap under the scopes ocular lens, which will determine if it will clear your handguards or barrel. 