Gauging of magazines can be a point of contention at times, especially when a magazine appears not to fit the gauge. In this NROI Tips video we cover how to properly use a magazine gauge with other important tips below the video.
One of the most asked questions concerns putting pressure on the magazine to make it fit. Appendix E1 in the 2019 USPSA Competition Rules outlines the procedure for measuring a magazine using either a ruler or tape measure and the official USPSA magazine gauge. Note that the rulebook allows for applying “slight pressure” to the magazine in order to determine if it fits or not. This is typically considered to be light finger pressure and not a “Captains of Crush” killer grip, but the fact is that if a magazine doesn’t fit, there is no way to apply enough pressure to make it do so. Because magazine lips can be slightly deformed, followers can stick up, and base pads can be slightly loose on the bottom of the tube, on occasion a slight amount of grip pressure must be put on the magazine to ensure it is touching the back of the magazine gauge. This is perfectly acceptable, and is demonstrated in the video. Due to lighting effects and shaky hands, there appears to be a slight gap, but rest assured the magazine used fits the gauge with only slight pressure, and while barely legal it IS legal. If your magazine appears to be too long when checked, ask for the Range Master—as in many USPSA calls, his will be final, but don’t be afraid to ask for a little pressure, either.
Note that the actual length of both sides of the magazine gauge is 1.25 mm longer than the nominal 140- or 170- mm length that IPSC specifies, being 141.25 mm and 171.25 mm, respectively. This was intentionally put into place years ago to allow for manufacturing tolerances of both tubes and base pads. If you are an international competitor, note that IPSC has no such tolerance on their length requirements, therefore their maximum length is 140- or 170-mm.
Some manufacturers sell base pads with the notation “SNL” on the pad. This isn’t a reference to a popular comedy show, but rather an acronym for “Sometimes Not Legal”. The reason for this is variance in tube length from different manufacturers, so be sure to check your magazines before having them gauged at chrono and finding out that they aren’t legal and you’re either bumped to Open or shooting for no score. It’s surprising how many people ignore this requirement when building an Open, Limited, L10, or Carry Optics gun. Also, be aware that a 170 mm long magazine is legal in a single stack 1911 pistol being used in Limited and Limited 10.
Know before you go is a good aphorism competing in either USPSA or IPSC matches. Measuring your magazines prior to the match, especially if you’ve changed or added base pads, can make all the difference in the world. Investing a few dollars in an official magazine gauge may be wise—it’s a handy shop tool to have around. Remember that any magazine used in the match can be checked at any time and it only takes a millimeter to ruin your day.
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