I have a Weaver 4-16x42 with A/O on mine and it just barely fits. Heres the measurements for it.

Tube Diameter: 1"
Objective (front) Diameter: 52 mm
Ocular (rear) Diameter: 38 mm

Adjustable Objective: Yes
Adjustment Click Value: 1/4 minute of angle
Eye Relief: 3.1"

Field of View at 100 Yards:
[*]27 feet @ 4x[*]7 feet @ 16x

Lens Coating: Multi-Coated

Length: 13.9"
Weight: 16.5 ounces

Hope that helps a little