So, being new to flintlocks I just learned that the breach plug when tightened into the barrel must contact two (2) shoulders at the same time. One shoulder is in the base of the barrel where the breach plug threads stop and the rifling starts. The other shoulder is simply the end of the barrel.
The purpose, it seems, is to achieve two (2) metal-to-metal seals - one at each of the shoulders mentioned above, which seems difficult to achieve.
However, I've read that if the touch/vent/flash hole intersects the breach plug it's no big deal, merely grind a groove in the plug to allow the touch hole to communicate with the powder charge in the barrel. But in doing so, you lose one of the metal-to-metal seals. So presumably one (1) rather than two (2) metal-to-metal seals in acceptable?
Also, a face seal is not a very efficient seal for this application and trying to achieve two (2) of them simultaneously is beyond good engineering practice. Has anyone ever explored a single tapered metal-to-metal seal?
Perhaps a tapered seal is just too nontraditional for this application?
Am I asking too many questions?
Jason
First traditional gun making is not "engineering practice" its gun making. Engineers and machinists are not gunsmiths and many times do not understand the reasons for why things are done as they are. I am sure some engineer or machinist, for example, decided that it was more efficient to install TC "Hawken" breeches to high torque that stretched the rebated section so that if removal was attempted the rebate would break off. But it was "efficient" from the standpoint of modern manufacturing.
"Not very efficient?" Yeah its a lot of work especially the first time or two. But one must remember that by MODERN standards a FL is horribly inefficient. Both is operation and in construction which is far more labor intensive than a modern designed to be made with minimal labor.
The face seal is actually very efficient when done right and perfectly seals the threads from any gas/fouling intrusion or in some cases gas leakage that can actually cut the threads.
A tapered, i.e. pipe thread will seal gases and liquids, however, it LEAVES FOULING TRAPS since the threads are invariably deeper than the plug this is VERY dangerous give the corrosive properties of some propellants used in ML arms.
Given the leakage inherent in modern thread tolerances and the possibility of chlorate fouling from a propellant its a huge mistake to allow gas intrusion into the threads or any fouling trap at the breech even if building a FL since people use it in FLs with a BP booster charge.
Our modern materials and tolerances designed for mass production and interchangable parts sometimes produce problems that were not seen back in the day. AND there were problems back in the day. People killed or injured by breech failures for example. The idea of royalty being killed was likely the reason Europeans set up proof laws.
There are things that worked well in the past with more ductile materials, i.e. iron as opposed to cold rolled steel, allowed things like unsupported drums in drum and nipple guns. With the materials used for these today an unsupported drum will sooner or later break off and depart at significant velocity. This is not supposition. So when we speak of doing things as they were done in the past, tapered breech threads for example, we have to under stand that compared to a propellant with high levels of Potassium Chlorate. There are various horror stories out there. Things that Mad Monk told me would happen decades ago have occurred. I.E. pits eating their way out to cause gas escape. People talk of originals with no shoulders, this is true. But BP is relatively benign and so long as the barrel is not threaded deeper than the plug. This error is not uncommon in modern ML barrels sold to builders with breeches installed. This enhances leakage into the threads and creates a fouling trap/patch grabber at the breech if tapped deep enough.
Cutting grooves in breech faces also produces leaks and traps. Its bad practice.
Dan
