Ever wonder if your reloads meet SAAMI minimum chamber dimensions? Then this is the gage for you. Min Dimensions Gages are made to SAAMI specifications for Min Chamber.  SAAMI Min Chamber specs are slightly LARGER than Max Cartridge.  The purpose of this gage is to check your reloaded rounds to see if they meet Min Chamber Specs.  Therefore, if your rounds do not enter the Gage, then this is pointing to an issue with your reloaded round against SAAMI specifications. On the other hand, if your rounds DO enter the Gage, but DO NOT chamber in your gun.  This points to you having a very tight chambered gun and would assume either an improperly cut reamer or a chamber that was cut below Min Chamber Dimension headspace. This does NOT mean that your round will not chamber in your specific gun's chamber.  This only means the round DOES NOT meet SAAMI Min Chamber dimensions and is telling you to take another look before deciding that your round is good to fire.