Not that it matters, but does anyone even want a bump stock? I've never heard of anyone that does.
Ask that to all the dumazzes bidding on Gunbroker. Prices are going north of $700, for a piece of plastic.
I guess they don’t know you can accomplish the exact same effect with a wood dowel of the right length. You can even affix it to the stock if you don’t want to have to deal with carrying the dowel separately.