Jim -
Sorry to have missed your query on the vent the first time around. I had just found the image of the Bouché or Vent Liner a few minutes ago and tried to post an image but think I had one too many Sarsaparilla's along the way. It wasn't that fuzzy when I opened it in Photoshop. The vents were "spec'd" at 20/100 - allowing "windage" or clearance of 1/100 over the stated maximum diameter of 19/100 for "finished" quill primers as I recall. I have in the notes somewhere the "not to exceed" size allowing for erosion - I think it may have been in Dahlgren's 1852 treatise on gun locks and primers. In any case, excessive erosion led to hairline fracture(s) which led to tube failure at the breech which was hazardous to the crew which was also irritating as all get out to the gun crew for some reason. The threaded section at the top was supposedly soldered in with platinum solder, and when required, this "bouché" was to be heated, removed, and replaced. Whenever I can find that passage again I will post it here - hopefully in a more timely manner.
Thank you for your patience.
Bill
