If your just checking for unsafe chamber dimensions what you need is a field gage. If the bolt closes on a field gage the gun is not safe to shoot. A field gage is the exact maximum safe saami dimension for a given caliber.
To do any gage tests on a ar15 the ejector needs to be removed.
Go gage is the shortest safe saami spec that allows ammunition made to saami maximum spec. field is the longest safe chamber dimension. Go and Nogo gages are typically used when cutting a chamber to spec or setting head space on adjustable rifles like the savage series.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
Last edited by JonM; 02-25-2013 at 02:35 PM.