Product Review

In order for a gauge to indicate correctly in this application, it needs to be an exact .001" fit and perfectly straight with no play when everything is in alignment. This gauge is machined to be a perfect .001" fit with the carrier key. Made from hardened and polished tool steel. Gauges have to be hardened so they stay straight with use and will not flex in use. In order to achieve best accuracy the gas tube should not contact the barrel nut teeth on either side when it fits centered in the carrier key. With the fit of this gauge you can see the variance of the space on either side of the gauge to the barrel nut teeth for perfect alignment of the nut with the hole in the carrier key. Made in USA and sold only direct from AR Specialties LLC. AR Specialties does not have any other resellers on Amazon for this product. Ships in the USA only no export or APO/FPO