Sinclair #35 Shoulder Bump Gage Insert, 35 Deg, 30 Nosler/284/WSM

Description

If you're chasing consistent brass life and tighter headspace control, the Sinclair #35 Shoulder Bump Gage Insert is the little piece that makes it happen. This is a 35-degree insert cut to match the shoulder angle of the 284 Winchester and WSM family of cartridges, so it indicates off the shoulder of your case rather than a sharp datum line. That tapered design gives you a cleaner, more repeatable number when you're figuring out exactly how far you've pushed the shoulder back.

Unlike a square-cut comparator that bites into one point on the shoulder, this insert is machined with a taper that more closely mimics the way your chamber actually contacts the brass. The result is a measurement that's easier to read and easier to trust when you're setting up a die for the first time or checking a batch of fired cases against sized ones.

What the Sinclair #35 Bump Gage Insert Covers

The 35-degree angle makes this the right insert for a wide spread of popular magnum and short-mag rounds. It handles the 284 Winchester, 270 WSM, 7mm WSM, 300 WSM, 325 WSM, along with the 26 Nosler, 27 Nosler, 30 Nosler, and 33 Nosler. If you load any of the WSM or Nosler family cartridges in that group, this is the insert you want on your bench.

Setting Up Your Full-Length Sizing Die with the #35 Insert

The workflow is straightforward. You install the insert into a comparator body, clamp the body to your calipers, and measure from the case head to the shoulder datum on a fired case. Zero your caliper, resize, and measure again to see exactly how much bump you've got. Most bolt-action reloaders aim for about .001 to .002 inches of bump, while semi-autos typically want a touch more. Keeping that number minimal is what stretches brass life, tightens your groups, and keeps your headspace honest.

Fits Sinclair and Hornady Comparator Bodies

This insert is machined to drop into either a Sinclair comparator body or a current Hornady Lock-N-Load comparator body, so you don't have to commit to one brand's ecosystem. Keep in mind the insert reads off the shoulder, which is a different reference point than a square-cut Hornady insert, so always build your data fresh when you switch tools. It's a small, precise piece of stainless hardware that earns its spot in any precision reloading kit.