So, I have a mix of 20" and 18.5" pump shotguns. I'm curious what the limiting factor is on magazine capacity. What I mean is, why can I fit 7 rounds in my other 18.5" shotguns, but NOT in my Remington 870? I have a Benelli Nova Tactical that can hold 7 in the magazine. The magazine extension is flush with the end of the barrel. I have a Hawk Industries 982 that can hold 7 in the magazine, and it's a blatant copy of the 870. It also have an 18.5" barrel with an extension that's flush with the end of the barrel. I have a Pardner Protector that can hold 7 in the magazine, and it's another blatant copy of the Remington 870. Then I have a Mossberg 590 that holds 8 in the magazine.... But my Remington 870's with 20" barrels only hold 7, and so does my 20" barreled Maverick... What is the difference? The magazine tubes are all the same length, right? Just wondering. Thanks. Sam Wanna kill these ads? We can help!