bapfreak, hello. The detents you describe are easily removed from the magazine tube of the 870 Express and while most models have them they do not all. I got the 870 security model from a Big 5 , a California chain, and it does not have those detents. Some drill them out, some use a dremel, others use a dremel and a drill, and others knock them out with socket wrench.
If you don't want to deal with the detents, I suggest picking up an 870 that came out of the factory with either a Remington 2 shot or 3 shot extension.
Last edited by TheKlawMan; July 17, 2011 at 12:04 AM.