PainIs4ThaWeak

I'm assuming the OP's intention is to not use the Chaos rail system with the H&K sights? (Might be stating the obvious, but If using the Chaos rails, the holes are pre-drilled for the H&K sights.)

As a new S-12 owner, I believe this whole thread is relevant, IMHO. Thanks for the info everyone. I'm off to get a Polychoke II

Glad you dig it OP. (Just seeing this for the first time today). Stinks that people like me (left handed firers) would probably get hit with ejected casings with rightwards ejecting bullpups. :\