I finally got to the range a few days ago to test my 507K with the circle/dot reticle. I had previously sighted it in using only the 2 MOA dot. The circle is 32 MOA which is 16" at 50 yds, 8" at 25 yds and 4" at 12.5 yds. My theory was that I should be able to put the circle on the upper chest of an IDPA target at any distance out to at least 25 yds and all rounds would land inside the 8" 0-down ring on the target. My theory was correct, but that's only part of the story. The sight is fast, amazingly fast! Our monthly IDPA match Saturday, Nov. 28th was rained out, so I didn't get a chance to test the reticle further under match conditions. I suspect my times and points-down will be significantly lower.
I must confess that I thought the circle or circle/dot reticles would be pretty much useless on a handgun. I'm happy to be wrong. For people unfamiliar with IDPA targets, the 0-down ring on the target is in the upper chest in an area that contains the vitals that would most likely end a deadly threat. (Click on the target to see a larger version.) Being able to rapidly put rounds in the 0-down ring at virtually any reasonable pistol distance is not only a major benefit in a match, it might mean the difference between going home or going to the morgue if you face a deadly assault.
I plan to test this theory at 50 yds where the circle will be 16". That's still 2" less than the industry standard of 18" shoulder-to-shoulder for an average man. The vertical mark at 12 o'clock should make lateral alignment easier as you can simply align it under the head. It obviously won't work at 100 yds. but a pistol fight at that distance is highly unlikely.
Chas.
