Geissele SAG .408 Suppressor Alignment Gage 10-1640-F

The Geissele SAG .408 Suppressor Alignment Gage 10-1640-F answers a question that matters more than most shooters realize: is the suppressor actually lined up with the bore, or just threaded on and assumed to be straight? A small deviation at the mounting interface doesn't stay small. By the time it reaches the suppressor's exit hole, that tiny offset has compounded into something that can mean baffle strikes, decreased accuracy, or worse.

This Geissele SAG .408 Alignment Gage is manufactured from hardened steel, ground 0.002" under nominal bore diameter, a tolerance Geissele found fits the widest range of barrels without needing an impossibly tight fit. The outside diameter is finely finished and held straight to 0.001" over its full length, and at 17" long, the gage is long enough to align itself naturally to the bore rather than requiring a snug fit to read accurately. Hardening the steel also means it won't wear from sliding through abrasive powder residue, and it won't pick up burrs if it happens to catch on misaligned baffles.

Using it is straightforward: with the weapon unloaded, the SAG slides through the bore and out through the suppressor, and where it exits tells you whether everything downstream of the muzzle is actually concentric. This suppressor alignment check takes a few minutes and can catch a problem before it becomes an expensive one.

For anyone running a suppressor seriously, whether that's a single host rifle or a rotation of several, this Suppressor Alignment Gage is the kind of tool that earns its keep the first time it catches something off.

Key Features

• .408 caliber, 17" length
• Manufactured from hardened steel
• Ground 0.002" under nominal bore diameter
• Outside diameter straight to 0.001" over its full length
• Resists wear from abrasive powder residue
• Verifies suppressor-to-bore alignment before firing
• Long design self-aligns to the bore without needing a tight fit
• Made in the U.S.A.