Sinclair #17 Shoulder Bump Gage Insert, 17 Degree, 30-06 Springfield

Description

Getting your shoulder bump right is one of those small details that separates brass that lasts and chambers smoothly from brass that gives you headaches. Sinclair's #17 Bump Gage Insert is built to help you nail that number. It installs in a Sinclair or Hornady comparator body and is machined to match the 17-degree shoulder angle found on the 30-06 family of cartridges, so you can measure exactly how much you're pushing the shoulder back when you set up a full length sizing die.

What the #17 Shoulder Bump Gage Insert Does Differently

Rather than reading to the datum line, this gage indexes off the shoulder of the case itself. That gives you a cleaner, more repeatable reference for how much your die is moving the shoulder. Clamp the comparator over your caliper jaw, zero it on a fired case, then measure a sized case and the difference tells you your bump. A common target is around .001 to .002 inches for bolt guns and a bit more, roughly .003 to .005 inches, for AR-style rifles.

Cartridges That Fit the 17 Degree Insert

The #17 covers the whole 17-degree shoulder group, not just 30-06 Springfield. That includes 270 Winchester, 25-06 Remington, 280 Remington, and 7.62x39mm. If you reload across several of these, one insert handles the lot, which makes it a handy piece for a bench that sees a mix of classic hunting cartridges.

Machined from stainless steel and marked with its shoulder angle, it's a simple, durable tool that does one job well. It's also a smart way to keep track of brass and loaded rounds when you've got more than one rifle in the same chambering, since checking your measurements keeps everything organized and consistent on the reloading bench.