I imagine you could call and special order one with a 1-7" twist... my understanding was that if its some combination of features they already catalog (not necessarily in the same gun) it should be achievable. Since they have the 12 F/TR .223 Rem with a 1-7" twist...

My concern would be whether it would feed worth a dang. I've had a 24" LW .223 Rem barrel with a 1-8" tw in the past, shooting B80VLDs very well (despite a rather short throat for that kind of bullet)... but the problem was that the rounds would feed up and then butt right into the back face of the barrel, a little over 1/16" below the chamber. Single-load slow-fire it wasn't too bad, as you could reach up with a finger and snake the round up into the chamber easily enough, but for mag feed... it'd be a no-go.