Jim Watson -
I realize this string is old now, but your reply is incorrect; i only know because I recently learned that I had misunderstood this rule as well.
I shoot a Walther Q5 Match SF. Love the pistol; hate the stubby magazine release.
I ordered an extended mag release from Walther, and used my dremel to remove the lip from the top of extension (to keep in line with the 'not oversize in diameter' part of the rule). http://www.carlwalther.com/images/q5_round_mag_release.jpg
Like you, I logically thought the rule was limiting how much LONGER THAN THE ORIGINAL the mag release could be; seems a reasonable frame of reference. But as elguapo points out, the rule is incredibly clear. The .2" is the absolute limit the release can extend from the frame, measured from the rear-most spot on the release.
I remain perplexed by the intent of this rule; I certainly wouldn't EDC a pistol whose magazine release I couldn't easily and reliably manipulate under stress, and the extended release from Walther is great in that regard. I had to remold my Kydex holster to accommodate it, to be sure, but of course would do the same for an EDC pistol as well.
Nonetheless, that is the rule. The Walther extended release, in addition to being oversize, extends about 0.318" from the frame, while the OEM release extends about 0.117" from the frame.
Hoping to shoot at my state IDPA match in 2021, so now I'm in search of a machinist to help me make a mag release as long as is legal. Thinking I would start with the Water extended release, disassemble it, grind stuff down, and attempt to reassemble. Unfortunately at the moment I don't have access to my workshop / materials, so I can't easily do it myself.
