Sinclair International Hex Style Bullet Comparator #2 17-338 Caliber

Precision reloading starts with accurate measurements, and the Sinclair International Hex Style Bullet Comparator #2 is built for handloaders who refuse to guess on seating depth. This stainless steel comparator works with your dial or digital calipers to measure the distance from the bullet's major diameter to the case head—a critical dimension that directly affects accuracy and pressure consistency. Unlike comparators that clamp to your calipers, Sinclair's design keeps your measuring tool free for other tasks, making your workflow faster and more flexible at the bench.

The #2 model is engineered for mid-to-large caliber work, covering the .172, .204, .224, .270, .308, and .338 caliber range. Each hole is precisely throated using reaming tools that mirror actual rifle chamber throats, so your measurements reflect real-world performance in your gun. That accuracy matters: even small changes in seating depth shift velocity and pressure, which is why Sinclair has refined this design over more than two decades. The hex-shaped body provides a stable platform and keeps the comparator from rolling on the bench.

If you're handloading for precision rifle, competition, or hunting loads where consistency wins, this comparator eliminates guesswork from the seating depth equation. Pair it with quality calipers and you'll dial in loads that shoot the same from round to round, load to load.

Key Features

• Covers .172, .204, .224, .270, .308, and .338 caliber bullets
• Stainless steel construction for durability and corrosion resistance
• Precision-throated holes engineered to replicate actual rifle chamber geometry
• Works with any dial or digital calipers—doesn't attach or clamp
• Measures bullet seating depth accurately for consistent handloads
• Hex-shaped design for stable bench use

Specifications

Frequently Asked Questions

What calibers does the Sinclair #2 comparator fit?

The #2 model features throated holes for .172, .204, .224, .270, .308, and .338 caliber bullets. If you reload smaller calibers like 6mm or 6.5mm, you'll want the #1 model (09-600) instead.

Do I need special calipers to use this comparator?

No. The comparator works with any standard dial or digital calipers you already own. It doesn't clamp or attach to your calipers, so you can use the same tool for other measurements without swapping accessories.

How does this improve my handloads?

By measuring from the bullet's major diameter to the case head, you get an accurate baseline for seating depth. Sinclair's precision-throated holes replicate your rifle's actual chamber throat, so your measurements translate directly to pressure and velocity consistency. That means tighter groups and more predictable ballistics.

Is this the same as a headspace gauge?

No. A bullet comparator measures seating depth to help you set your reloading press correctly. It's an essential tool for anyone who wants repeatable, accurate handloads.