Has any one shot one of these JR Carbines, they look great, have interchangeable parts from the AR, comes in 9,40,& 45 and excepts all the glock mags. I have 2 sub 2000 ( 1 is a 9 glock and the other is a 40 in s&w mag ) but i want a sub 2000 40 in a glock a mag but if I cant get one then I might get one of these. Cost though is $700