The most common ways to create an enclosed track are: a UHMW or Delrin strip installed in a wood stock. Or cast in some Epoxy, or epoxy mixed with graphite, then cut the track with a router. I imagine there are advantages to each solution. and the low friction of UHMW is probably desirable. I only have experience with open tracks, so I have no idea.
Does it make any sense to utilize sheet metal for an enclosed track? I have a drawing here to illustrate the idea. It would be a piece of 20 or 22 gage SS sheet, bent with a brake the entire length(open at muzzle end). The concept is that the track only needs to ever contact the shaft at 3 points to control it. In this way we keep water all around the shaft, and avoid friction with limited contact area.
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