I have a Sig P220 with a nickel slide almost new, only 50 rounds put thru it. But, I can't keep the top of the barrel from rusting. So I went to the local gun shop and told the man working there my problems and he said he would trade me my Sig for a NIB HK USP .45, should I take the trade ? How reliable is the HK ? Will it rust ? Any advice would be helpfull