I'm in the process of buying a Benelli M1 witha standard stock and rifled sites. Were can I get a good folding stock? Also, which site base is best for mounting a descent site.
You won't find a folding stock for your Benelli because Benelli semi-autos all have a recoil spring tube projecting back from the receiver into the stock.
That's the physical reason.
The legal reason is because imported semi-auto shotguns can't have pistol grips and folding stocks, according ro rule 922(r).