Before I retired I was the weapons officer in our area. The CHP has Rem 870's in all patrol vehicles, they are ALWAYS loaded with four rounds (no mag extensions for us...). Quarterly I would clean the weapons and change the ammo for new. I have NEVER heard of a 870 failing to feed due to a mag spring. One problem we did discover is that in the summer, with the temp soaring inside of the locked vehicle (assuming that it wasn't used the entire day), the bottom round in the mag (first to feed) would get "soft" from the heat, and the spring tension, would cause the round to bend a little, right at the top fo the brass. I never found one that would not feed, but started changing the ammo monthly in the summer months. Something for those of you keeping a shotgun in the trunk to think about...<br><br>The CHP issued S&W 4006's about 12-13 years ago. Each officer was issued three standard "duty" mags, and each weapon also came with three red based mags for training use. During the initial training with the weapon each officer was allowed to load and shoot dry the three duty mags one time. After that the idea is that those mags will never be used again, unless in a combat shooting. Officers are supposed to empty and clean the mags at least weekly, and at the monthly shoots the ammo will be stripped out of the duty mags and fired. Fresh ammo will then be loaded into the duty mags. I don't necessarily agree with this idea, but for some reason they didin't ask me... Again, I have never heard of a failure to feed caused by the mag spring.