New M&P15, a few questions.
I have a brand-new Smith & Wesson M&P15. Two guys at the shop where I purchased it gave me conflicting information on how to use it to start. First, the guy said to just shoot it and have fun. No special new-gun treatment. Another guy came up, said that was wrong, and I should clean the rifle after each shot for the first 20 shots. What gives?
Another question, all my magazines are marked 5.56x45. Call me silly, but I assume this is referring to the diameter of the casing, and not the grain of the projectile. Am I correct?
Any other advice? Been a long time since I cleaned one of these for Uncle Sam, any new tricks, things I should/shouldn't do?