Yep your right
Why dont you see many HK's in IDPA and IPSC? Because there are much better guns to shoot those matches with. The USP series of pistols are expensive and have only ok triggers that gunsmiths can't or won't attempt to do trigger jobs.
There are some Sponsered HK shooters who use the USP Expert in Limted Division for IPSC. But man HiCaps aren't cheap and neither is the gun.
Ipsc and IDPA are ruled by 1911's and Glocks. Why because they are easy to find, Lots of smiths and armorers work on them. Mags are cheap and availible.
HK's dont have any of that going for them.
Me I shoot a CZ75 ST IPSC with a 1.75lbs trigger and 16 round mags in IPSC and a 1911 with some custom work in IDPA.
Both guns together probably cost me less than a USP Expert.
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