I like to keep 2 or 3 magazines (8 round) loaded with JHP in the unfortunate event that I need them. My question is how long can you keep a high quality mag (eg. Combat Wilson) loaded before it may become unreliable? If this question has been answered previously, I apologize. Thanks! Also, I was told by a clerk in a gun store that it's better to load only 7 rounds in an 8 round mag to help keep the spring strong. Is this true?