The tritium is dim, does not work with hk usp 9 - Meprolight Night Sights for HK Pistols and Handguns

The tritium is dim, does not work with HK USP. The HK USP 9 back slot spacing is deeper then the sight block goes down. The tactical USPs setup must not be the same spacing in the back block. Maybe it was a defective item. I used a sight block, puller and pusher and have done 4 this year that work for other guns.