Hastings makes a replacement barrel for the Auto 5.
Bought one years ago in the US, before all the silly Home Land Rules came into effect.
Vent Rib and chokes, very good deal then, should be cheaper now with our stronger dollar.
Of copurse that is if the retailer is passing that along to you.
Did you try Whole Sale Sports cause I am sure I saw those barrels in there not to long ago.
The only thing I can think of that will throw a wrench into this is that your Auto 5 is a 16 gauge ....
There is still time before Pheasant season...Good Searching.
Was just on the WSS home page and there are barrels for BPS and Rem.1100s, so there might be hope for you yet.
Rob