The L.E. Wilson Minimum Chamber Gauge is made with the same tight tolerances you have come to expect from all your Wilson Tools. Best used if you are loading ammo to work in multiple gun chambers of the same caliber. Wilson recommends using this in conjunction with the Regular Case Gage to prevent over-sizing. Gage verifies Min Chamber Dimensions and OAL for SAAMI.
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.
Reasons to use the Min Dimension Gage
1) You want your reloaded rounds to chamber in a variety of guns
2) You want to check for uniformity of your rounds against SAAMI specifications
3) You want to pinpoint issues with your reloaded ammunition
4) You want a quick check to see if you are under MAX SAAMI COAL
5) You want to check factory ammunition you have purchased
NOTE: Check with your bullet manufacturer to verify OAL this will vary depending on what grain and style bullet you are using. Min Dimensions Gages are made to SAAMI specifications for Min Chamber. SAAMI Min Chamber specs are slightly LARGER than Max Cartridge.