Brownells sells a throat erosion gauge. I bought one a few months ago to keep track of the throat erosion in the ARs that I want to keep accurate (3gun rifle and my wifes Noveske). Brother LukeMacGillie told me of them.

Mfr: MERCHANT
Instant Read-Out Checks Throat Wear
Presents a quick and accurate indication of barrel/throat wear. Use every 1000 rounds to obtain a comparative reading of throat erosion. Provides match and varmint hunters an easy, convenient method to determine remaining barrel life. Fits semi-auto and bolt action, .223, .222 and .22-250.
SPECS: Steel. 3-7/8" (9.8cm) long. Includes complete instructions.
Catalog page 45
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
Bookmarks