A barrel seal activator is used on the Model 11-87 12-gauge Super Magnum shotgun to improve performance when using light 2-3/4" loads. The barrel seal activator takes up the initial volume in the gas cylinder forward of the barrel seal Seat. It in essence nullifies the compensation system so that all of the gas on the light loads goes into cycling the action. When using extremely light loads, this eliminates power related malfunctions: such as not having enough bolt velocity to fully cycle the action or not allowing the action to completely lock open after the last round is ejected. It also positively seats the barrel seal and protects it from heat, which helps in prolonging its life. Removal of the barrel seal activator is recommended when using 3" or 3 1/2" loads.