Arsenal has not built any stamped 5.56mm rifles yet, one thing to remembver, especially about Horton's, is that the sales people are not "gun" people most of the time, and they have A LOT of product to remember and all they know is what their computer is telling them.
Hopefully, Arsenal Inc. will introduce a stamped series of 5.56mm, and I'll be in line in a heart beat for one.
Hopefully, the SLR-107A1 and SLR-108's will be available soon, but again, they are entirely dependent on the Bulgarians on this.
Here are some factory pics of Arsenal 5.56 stamped guns.
AK-74M1A1 Pattern 2
AKS-74M1A1 Pattern 2
My AKS-74 M1A1 Pattern 1
The reason I like mine is because of the reduced weight which makes a difference for carrying in the field. It weighs almost the same as an M4A3 but is much more reliable and just as accurate. True the milled guns are more robust but a stamped gun will last just as long and is cheaper to produce. Honestly I would love to see Arsenal BG start producing stamped 5.56 guns that are affordable for everyone. Mine was a project that started over seven years ago and no Arsenal BG doesn't even have one in their military museum collection as Templar pointed out.