Brownells Rifle 3/8'' X .125'' Aperture Peep Black

A Brownells Rifle 3/8'' X .125'' Aperture Peep in black is a replacement rear sight disc engineered for shooters who need precision aiming without electronics or complicated adjustments. If you're running a Williams Foolproof, Target Foolproof, or 5D rear sight and your aperture disc is missing, damaged, or worn, this individual aperture gives you a straightforward way to restore or upgrade your iron sight setup. Whether you're sighting in a hunting rifle, working precision targets at the range, or maintaining a backup sight system, the right aperture makes the difference between guessing and shooting.

The 3/8'' diameter aperture opening provides a clean sight picture for mid-range and longer work, allowing more light to reach your eye while maintaining the precision that peep sights are known for. The .125'' thickness is standard for Williams peep sight architecture, ensuring a drop-in fit on compatible receivers. The black finish is durable and non-reflective—no glint, no distraction. This is a no-frills component: it does one job well and costs far less than replacing an entire sight assembly.

Brownells apertures are built for hunters and shooters who understand that sight reliability isn't negotiable. Keep a spare in your range bag or use this as your primary disc if yours has taken damage. Works exclusively with Williams Foolproof, Target Foolproof, and 5D sights—verify your sight model before ordering.

Key Features

• 3/8'' diameter aperture opening for clear, precise sight picture
• Standard .125'' thickness—compatible with Williams Foolproof, Target Foolproof, and 5D sights
• Black finish resists glint and corrosion
• Individual replacement disc—exact match for missing or damaged apertures
• Simple, tool-free installation on compatible sight bases

Specifications

Frequently Asked Questions

Will this aperture fit my Williams rear sight?

This aperture is designed for Williams Foolproof, Target Foolproof, and 5D sights only. Verify your sight model before ordering—the standard .125'' shank fits these three models. If you have a different Williams sight or an aftermarket base, check compatibility first.

What's the difference between aperture sizes?

The 3/8'' diameter controls how much light enters your eye and affects sight picture brightness and precision. Larger apertures admit more light (useful in dim conditions) but may reduce target definition slightly. This size is a versatile middle ground for hunting and range shooting. Other diameters are available separately if you need a wider or tighter opening.

Is this a complete sight or just the disc?

This is the aperture disc only—the replaceable sight element. You'll need an existing Williams Foolproof, Target Foolproof, or 5D sight base and shank already mounted on your rifle. If your entire rear sight is missing or broken, you'll need a full sight assembly, not just the aperture.