I have read that Colt detachable carrying handles don't mix with the front sight height on other manufacturers barrels. I was about to order a barrel but am not sure who made the carrying handle that I have. The only markings on the handle were just in front of the rear sight on the left side. The markings were either "A-I" or "A-1" inside of a circle. Can you tell me who made this detachable carrying handle?