No, only the 20" models with the two barrel guide rings have a bayonet lug on them. The 590A1 I bought was the 20" model with a bayonet lug, while it's cool, not a terribly useful feature at the end of the day.

I thought about pulling a James here and stating Trevor's answer as if I knew for sure, but that'd be dishonest, Trevor knows his stuff and certainly knows the weapons he owns, id take his word for it

Steven, unfortunately no Sir, only the 20 inch barrels have the bayonet lug.