I recently bought an 18 inch barrel for my 870 Wingmaster and am considering a magazine extension. I will probably get the Remington brand one. My question is which extension fits flush with the end of the 18 in. barrel ? The 2 round extension ? Thanks. UPDATE: This is an 18.5 inch barrel. I misspoke. I went ahead and ordered a 2 round Scattergun Technologies magazine extension for two reasons 1) I could not find the Remington extension I wanted for less than $20 more than the Wilson/Scattergun and 2) I've heard good things about the Scattergun extensions. Thanks again, Chuck Wanna kill these ads? We can help!