The Butler Creek Flip Open 39 Objective (Model: BC30390 / 30390) is a spring-actuated protective lens cap engineered for rifle scope objective bells. Designed with a base target interface diameter of 56.40 mm (2.220 inches), this friction-fit cover creates a watertight and airtight barrier using an integrated semi-O-ring seal. It shields optical glass from mud, dust, moisture, and impact during field transport, opening instantly via ambidextrous thumb tabs without requiring the shooter to break cheek weld or take their eyes off the target.

Key Features

• Instant Spring Deployment: Opens rapidly with light thumb pressure on dual ambidextrous finger tabs for rapid target acquisition.
• Silent Operation: Features an ultra-quiet hinge mechanism that prevents mechanical noise from spooking game at close range.
• Environmental Protection: Uses a tight polymer friction collar and semi-O-ring seal to exclude rain, snow, and fine dust.
• Sub-Zero Durability: Tested to resist embrittlement and operate consistently in temperatures down to -40°C (-40°F).
• Ultralight Profile: Adds less than 1 oz (28.35 g) of total weight to the optic, preserving the balance of the rifle platform.

Specifications

• Target Interface Diameter: 56.40 mm (2.220 in)
• Effective Fit Range: 56.15 mm to 57.04 mm (2.210 in to 2.245 in)
• Weight: Under 1 oz (< 28.35 g)
• Material: Rugged black polymer with steel hinge springs
• Operation: Mechanical spring-assisted flip-up
• Minimum Operating Temperature: -40°C (-40°F)

Who is the Butler Creek Flip Open 39 Objective for?

• Stalking hunters in extreme environments — Requires an airtight, moisture-resistant flip-open rifle scope objective cover to protect optics across dusty outback or wet alpine terrain down to -40°C while maintaining sub-1 oz carry weight.
• Precision rifle shooters — Demands a secure friction fit for optic objective housings measuring precisely between 56.15 mm and 57.04 mm, ensuring rapid, silent lens clearing without optical interference.

Less suitable for: Rifle scopes with an objective outer diameter exceeding 57.04 mm, which require a larger objective cover such as a Size 40 (57.2 mm) to prevent polymer fatigue, or optics with an outer diameter below 56.15 mm, which require a smaller sleeve such as a 53.3 mm (Size 34) cover to maintain friction retention.