I know rock river makes one, you can get the upper or the whole thing, now... purchasing one.... Good luck... Gun crazies are out in full swing buying three of everything...
You can call rock river and order one and have it shipped to a dealer. You will sit on hold for about an hour before you actually talk to someone. If you do speak with someone, they probably will put it on backorder for three years.
I have made several attempts to speak to anyone there.
I want to get one too, they are very neat. Big chunk of lead no doubt.
Like shooting a 45 ACP with twice as much powder in the case.
WOW... 458 socom.
If you get one let me know.