I want to get a P01 milled for a Holosun 507k. The holosun has a rear sight built in, so I am hoping to put the optic as far back as possible, so it interferes the least with the holster and belt line.
But a lot of folks seem to put the optic in front of the rear sight. Why do they do this, when the Holosun has a sight built in? Are there other advantages I'm not thinking of?