At the recent NAVEXFOR expo in Virginia Beach I was introduced to the Small Arms Collimator (SAC). It is an optical device that allows shooters to confirm zero and/or re-zero weapons without live fire.
Rather than batteries it relies on a Tritium light source so it can be used day or night. When properly employed the Collimator provides zero accuracies within 1 MOA. Since no rounds need be fired zero can be checked in the field and the SAC is not only compatible with iron sights but with optical and night vision sights as well. Additionally, it is available for a wide variety of small arms including the M16 family of weapons.
The SAC is manufactured in the UK by Pyser-SGI, Ltd and offered exclusively in the US by Telluric Group. Visit Telluric Group for additional information on the Small Arms Collimator.