16" mock dissy, midlength gas, front sight pinned at rifle length, heavy or bull barrel.

Are there any manufacturers making something like that.  I've seen a few that are all of the above, but with a lightweight pencil barrel.  I'm looking to get a handy semi-precision setup, with a short, thick barrel, and the longest sight radius possible for use with sights when I feel like practicing irons.

Does anyone know of something like that?

ETA:  I plan on using mostly 75 grain bullets with this one, so it's got to be 1/7" twist.

Maybe ADCO will have what you seek.

Like this?
http://www.aimsurplus.com/product.aspx?item=XSTU5950MOE&name=Spikes+Tactical+16%22+Mid-Length+GMP+5.56%2f.223+Upper&groupid=586

Yeah, very much like that but with a heavy profile or bull barrel.