I looked around the forum and couldn't find my answer. I'm new at this and was at a gun shop today that told me not to use the Winchester White Box ammo in my Glock or my wife's M&P because it is cheap dirty ammo. They said it really dirtys the gun mechanism, cause failures and wear. For target practice...and the wifey and I are doing a lot of practice...but we have money to spend on ammo...so a few extra dollars for something better doesn't affect us.....I don't want to waste money but would rather have a quality bullet go through our guns. What is the more cleaner, better shooting ammo,for target practice? Also while I'm at it what would be the absolute best SD ammo for a Glock G27 .40s&w and a M&P compact 9mm?