The side mount scheme of our shotgun SureShell shotshell carriers for the Mossberg 500/590 substitutes two custom-machined steel Chicago screws for the trigger pin. At the front of the mounting plate, custom retaining steel hardware is used with an elongated extractor screw and a machined key hole in the plate. The Mossberg 930 mounting system is similar, except it uses two sets of Chicago screws in place of the two trigger pins. The mounting plate was designed not to obscure the receiver serial number to make it easier for armorers to inventory their weapons. SureShell shotshell carriers for the Mossberg fit on the left side of the receiver only. You must use a tactical forend that does not significantly overlap the receiver, or a factory forend that is cut down appropriately. SureFire forends will work fine with no alterations.