TargetTalk

When you unscrew that little rail section (the “bridge”) on the KK500, it just lifts off and you can see the two screw holes underneath

For the Walther KK500, in standard condition it comes with two rails for the front rails: one on the front and one on the rear, so the sight blocks are the same height.

I just checked their website and socials-looks like Pilkguns is still up and running. Maybe their email’s on the fritz? You could try calling them or sending a message on Facebook/Instagram.