Sinclair International Bullet Seating Depth Gauge With Standard Guide

The Sinclair International Bullet Seating Depth Gauge with Standard Guide is a precision reloading tool designed to help handloaders find the exact length of a loaded round as it contacts the rifling inside your barrel. Whether you're tuning match loads for a bolt-action rifle, setting up a single-shot, or working with an AR platform, this tool removes guesswork from one of the most critical steps in accurate ammunition assembly. Built from quarter-inch ground and polished stainless steel, the gauge features dual-ended design: one end sized for 17 and 20 caliber cartridges, the other for 22 caliber and larger.

The kit comes with a Delrin action guide (0.690" diameter) that works with most bolt-action rifles, including Remingtons, Savages, Winchesters, and many Ruger models. The guide seats in the rifle's action to hold the tool perfectly aligned while you measure, ensuring repeatable, consistent readings shot after shot. Because you measure with your own fireformed brass and bullets, you get an exact, real-world seating depth for your specific rifle—not a generic estimate.

This is a workhorse tool for handloaders serious about precision. It pairs naturally with bullet comparators and quality calipers to establish base-to-ogive measurements that inform your entire reloading process. If you reload for AR-15, AR-10, or Tubb's 2000 rifles, compatible guides are available separately.

Key Features

• Quarter-inch stainless steel construction, ground and polished for durability and accuracy
• Dual-caliber design handles 17, 20, and 22+ caliber cartridges with single tool
• Includes Delrin action guide (0.690" OD) for bolt-action rifles
• Works with Remingtons, Savages, Winchesters, Rugers, and most other bolt actions
• Measure seating depth using your own fireformed brass and bullets for exact, real-world results
• Compatible with single-shot and AR-pattern rifles (guides sold separately for AR platforms)
• Enables precise base-to-ogive measurement when paired with comparators and calipers

Specifications

Frequently Asked Questions

What rifles does the standard guide work with?

The included Delrin guide (0.690" diameter) fits most bolt-action rifles, including Remingtons, Savages, Winchesters, and many Ruger models. Separate guides are available for AR-15, AR-10, and Tubb's 2000 rifles.

Can I use this for AR-15 or AR-10 reloading?

Yes, the gauge itself works with AR platforms, but you'll need a separate guide designed to insert into the back of the upper receiver. The standard Delrin guide included is for bolt-action rifles.

What calibers does this tool handle?

The gauge features two ends: one for 17 and 20 caliber cartridges, and the other for 22 caliber and all larger calibers.

How do I get accurate measurements with this tool?

Use your own fireformed brass and the bullets you're actually loading. Seat the action guide in your rifle, insert the gauge, and measure where your bullet's ogive contacts the rifling. This real-world approach gives you exact seating depths specific to your rifle. Pair it with bullet comparators and quality calipers for base-to-ogive measurements.