Why so few Middy's

[Pappabear]

It seems like many people are interested in Mid lengthed SPR's in the 18 inch class. Why do so few Mfg make these guns, as complete set ups, and so many people want them. I was looking at Denny's Customs Upper with Larue, Krieger...very nice. Was considering running it on my Colt A2 lower till I could get lower for it. (Sorry, Got off track for a second in fantasy land). I saw a Sabre yesterday, but does Colt, LMT, S&W etc make these guns as a standard offering. If no, why not?

[Parabellum9x19mm]

how do you feel about SPR barrels with an intermediate gas system or rifle length system? the only SPR barrel i've used has an intermediate system, but it works great. very soft felt recoil impulse.