In the ML era people were not shooting powder with very high percentages for potassium perchlorate that produces very aggressive fouling. Unlike BP fouling the fouling this chemical produces will rust under an oil film or at very low humidity. Look at the erosion around the drum on many percussion rifles from the past. This is chlorate salt corrosion from the chlorate caps (a slightly different chlorate than that in the "modern" BP replacement but only a couple of grains total material in the cap) eating away the metal. Flintlocks that have never been converted are not eaten away like this. If ONLY BP is used the risk of having fouling in the threads not so serious, its not likely to eat the metal to any great extent. The chlorate powder very likely will cause problems down the road if the bore is not eaten out first to the point its difficult or impossible to even load (I am sure this is what saves many people with Walmart special MLs from hurting themselves) and breech problems are not something I want to worry about. Since we cannot control what the customer shoots or how he maintains we have to take precautions.
The corrosion capability of this material has been well proven repeatedly by friends who have either used it or had customers use it. Some of this has been reported here IIRC. I have done testing with it and seen the results of customers of the company I used to work for using it. The neat part is that it can dissolve the steel and not even produce red rust. Shooting it can produce after rust for a YEAR (yeah a year) with repeated cleanings in a vintage rifle with a not so perfect bore (linked to chlorate priming). So allowing this stuff to get into some fouling trap anywhere in the "pressure vessel" is really scary.
The other problem with not sealing the threads is modern thread tolerances. Which while they allow interchangeable parts also allow massive thread leakage of gases or fluids. In the modern world the tap cuts threads several thousandths larger than the part that in to be turned into the hole. Is some cases, of the tap is upper limit and the part lower limit there can he a LOT of slop is a 1/4 vent liner for example This is especially important when nipples or vent liners are installed. If the nipple, for example, is not seated on a flat seat matching its flange it will leak cleaning fluid around the threads when plugged t o flush with water. So I use a piloted counterbore with a brass sleeved pilot to cut a flat on the patent breech for the nipple to seat on, only takes 10 seconds or so to do it right. I have had vent liners gas cut. While many here seem to consider seating to a shoulder an unnecessary bother one must consider the consequences.
While I admit that the sloppiest breeching is extremely unlikely to blow out (when new), and at least some barrel makers know this and as a result do really sloppy breeching jobs that result in really cool fouling traps that when removed loo like this.
This is the plug I pictured earlier before I cleaned the fouling off. Now I am SURE that its impossible to blow it out (when new anyway) but I still have "trust issues".
One should ALWAYS work to a higher standard when human life is at stake. But the folks that make MLs and the parts that go into them don't seem to get it in far too many cases.
So we get poorly breeched barrels, locks from some suppliers with sear and tumblers so poorly aligned that they are not safe or will be unsafe soon after being put in service. But they have a customer base with, for the most part, no comprehension of liability and how far it can reach. Besides MLs never blow up. Everyone "knows" this.
Dan
