You sir are right. You can have them chromed but M1 garands were never chromed ,they didnt start doing that to infantry small arms until the M14 came out but WW2 is where they discovered the need to do something to prevent rusty bores and chambers.Tto tac 40 Im not saying it does but ive gone 1500 rounds straight without cleaning my AR and it has continued to function and ive gone 500 rounds and let it sit 3 months and it functioned next time I shot it,I did those as a reliability test to see, other wise I clean every time I shoot no matter what I shoot,but chrome unless you have an extreme amount of build up will continue to work where other unchromed weapons will fail,not all, but today is proof that if he had a chrome chamber it probably wouldnt have happened,if he cleaned it regularly it definately wouldnt have happened,but you can go longer with chrome.And also ive shot my AR in the rain plenty and have never seen the carbon get like tar,clp is a wet lube and water does not wash it away unless you keep it under water and it still wont wash all of it away,geting fine sand and dust in the action with alot of lube can cause this but ive never seen water do it and like I said ive shot in rain,The AR is an allweather rifle if a little water bothered it our troops especially seals would be in a lot of trouble and those guys are wet alot.And water from the air?do you mean humidity,because the M16 is also a great jungle weapon,if not maintained right in the desert it will give you problems but so will every other weapon if you dont take care of it,the conditons you desribe,"wet"the M16 has been tested in those areas a long time,thats why in vietnam befor chrome chambers soldiers never chambered a round and let it sit because moisture and wet from the humidity would make the round expand jamming the chamber,but chrome cleared that up.