I went with the bottom loading Hahn. Took my gun out for the first time today and it ran great. The Hahn bottom loading and dedicated both lock the bolt open after the last shot, the top loading does not.
I have a dedicated Hahn Block that I like very much which I use in my Dedicated SBR, for my FA M16 I use a top loading Hahn block. Ignore the ProMags, their junk. :mad: