WHAT DOES COLT COMBAT UNIT RAIL GUN 45 MEAN?

I've RIA drawings specifing barrel markings on a brand new USGI rifle and that marking is just not approved.Whether it is a bell condition, that would be proper for your Colt. And also the gas tube color and texture is fascinating. See Should the fuel tube will bring in a magnet and also to what diploma.     All the rest of the areas I see are Co