Chris
You are not wrong. They will all interchange since the hole pattern is the same. Burris just happens to make one that they say is for a carbine but their pistol mount will work on the carbine, there just is not much room between the rings for eye relief adjustment. I use Leopold scopes and the eye relief is long enough that the turret has to go against the front ring with the Burris handgun mount on a carbine (then the eye relief adjustment is borderline). Longshot has that base with a Nikon scope and it works fine because the eye relief is a little shorter.