There is no sure way. Remington says that it is OK to shoot that ammo but the gun may not function.. Most 12 guage mags will work with lighter loads but usually not with the lightest.. Clean the gun and lubricate it well will help but there is no guaranteed fix. Except!! Buy a 2 3/4 inch chambered barrel for the LT. Then all will be well. This was the biggest problem solved by the 1187..as it will function with either length shell.. Be careful Remington made 3 different 20 guage guns, standard 20, LT 20 guage and the Special Fields...