Very simple process. Drill another hole to match the existing port, and tap that hole for a plug screw. Don't know what else to add. I bought my 1000M new in 1977, and it has served me well for many years. The Magnum models are rugged well made shotguns. I have bought many guns since then...
Von, this shotgun is only designed to function with 3" Magnum ammunition. The skeet barrel with two ports will operate the action with lower powered shells. The magnum barrel only has one port. A popular modification back in the day was to drill an additional port in the Magnum barrel and...