I always understood an essential part of an army mounted pipe was the tapered tenon on the stem, that allowed the stem to be pulled when the pipe was hot and/or wet without eventually loosening up like a standard straight tenon. I owned several HCAs in the past (including an HCA 2), and they all had a metal capped shank, but a straight tenon like a regular pipe. The Savinelli Nonpareils alstenon to o have a straight tenon, but it is fit to a delrin mortise under the horn ferrule. Without a wooden mortise, I don't think they would have much of a problem if taken apart hot. The Peterson army mounts and systems have a tapered tenon, and can be pulled apart hot without any problems. If you like the looks of an HCA or Nonpareil, go for it! It's really kind of a moot point unless you plan to frequently be pulling the pipe apart hot. I smoke army mounts when I'm out in the boonies, because I don't carry pipe cleaners, and if I get a wet or plugged pipe, I can take it apart and blow the stem dry or unplug it on the spot.