Bushmaster and Beretta both have them, they are legal here in Texas to own price but legal. The Beretta has the enter change able parts with the Ar 15 M 16 type weapons. Both take the same mags. The Bushmaster was the first to maufactory them to give chopper pilots more fire power.
I do have a marlin in 45 Long Colt, was going to get into Cowboy Action shooting but, once I found out that to save time they drop their rifles and shotguns to get to the next firing stations I lost all interest. I have from to much money to drop my guns to save a few extra seconds of time. The wood on my Marlin is beautiful, so no I am not going to run around dropping my guns for a few second of time. Like all of us I have worked very hard suffered through many disappointments in this life. Like having to sell or pawn our guns for the good of the family to pay for food clothes, what ever.
Now that I am living a much better life, i am not faced with that any more and sure hope it never comes back, wouldn't wish those times on anyone.
I have never really thought about buying one myself but it does come to mind that a 45 acp. semi auto carbine would be one hell of a door greater. A passing thought put one of those cranks on it that sure have heck would lite them up lol.
It seems to me that there is more of a market for the CCW these days and Ruger just isn't going to go there, accept for the sp101.
But then again I guess it wouldn't do for me to be incharge of Ruger, as I wouldn't be letting Beretta and the others beatting my company at CCW market. And I would cracking the whipe to put all Ar's to shame at camp perry. But that is just me.