Had a conventional upper built with the new PRI Delta triangular forend. The top rail on the forend is higher than the upper receiver. Looking for front and rear BUIS that will work with the different rail heighth. HK parts.net has a Troy front sight that is .27 inches shorter than the standard Troy sight. Just wondered if I used the short Troy front sight and regular Troy rear sight, would they line up correctly.

I would think that by measuring the height difference you could determine the necessary offset for an even line-up.

Why not Contact Precision Reflex and ask them? They have Tech Support Staff who always takes care of me when I call! Call you will be surprised! My .02 M4QUADRAIL

This particular consideration has been discussed significantly in the "uppers, lowers" forum, and there unfortunatately doesn't appear to be a consensus best solution.

I do think that the PRi Delta forearms are damn sexy though.