Patent breach
- Thread starter vega
- Start date
The simplest muzzleloading guns just had the vent drilled into the barrel slightly in front of the face of the breechplug, whether flint or percussion.
In a patent breech, the vent communicates to a separate little chamber within the breechplug at the base of the bore. In a flint gun, the vent is made so that it is very thin, so the touchole itself has a very short passage. The combination of the thin vent and small chamber results in fast, positive, controlled ignition. This was thought to improve performance.
A patent breech is usually incorporated with a hooked breech, so the barrrel(s) can be removed for cleaning without tools. The hooked breech isn't a patent breech, although the two are sometimes confused.
In a patent breech, the vent communicates to a separate little chamber within the breechplug at the base of the bore. In a flint gun, the vent is made so that it is very thin, so the touchole itself has a very short passage. The combination of the thin vent and small chamber results in fast, positive, controlled ignition. This was thought to improve performance.
A patent breech is usually incorporated with a hooked breech, so the barrrel(s) can be removed for cleaning without tools. The hooked breech isn't a patent breech, although the two are sometimes confused.
Thank you very much for that info, I really appreciate it.
For greater understanding on my part, with a patent breech, I surmise you'd have to install the breech plug first then drill the vent so the hole in the barrel and the one in the plug would line up and give access to the powder chamber?
Also, I'm not getting what you mean by "thin." Seems as if the above is true, the length of the vent hole would be greater, not less? Unless the powder charge column exceeds the length of the chamber in the plug?
For greater understanding on my part, with a patent breech, I surmise you'd have to install the breech plug first then drill the vent so the hole in the barrel and the one in the plug would line up and give access to the powder chamber?
Also, I'm not getting what you mean by "thin." Seems as if the above is true, the length of the vent hole would be greater, not less? Unless the powder charge column exceeds the length of the chamber in the plug?
The flintlock vent is a bushing counterbored from the inside, connecting with a small lateral chamber. This is connects with the reduced diameter chamber in line with the bore. If you study an original, the touchole bushing in a quality gun is platinum, and there will be a large plug screw on the opposite side of the breech from the touchole which allowed access to the inside of the touchole during manufacture. The short passage allows the priming flash to enter the breech without a fuse effect. The powder in the chamber at the base of the bore produces an intense blast to ignite the main charge. In a percussion gun, the flash channel from the nipple connects to the chamber in the breech in line with the bore and the main charge. Ignition of the main charge is linear, rather than from one corner, which is what a simple touch hole or drum produces.
"Patent Breech", I believe is a contraction of reference to "Nock's Patent Breech". Nock,IIRC was an English gunsmith who came up with the idea to improve the speed of ignition in M/L guns. As mentioned above, a recess was drilled into the breech plug at a diameter smaller than the bore then the flash passage, whether flint or percussion was drilled through the barrel and breech plug into the recess. For example, in a 45 or 50 cal gun I drill the recess at 5/16" diameter then cone or counterbore the opening of the recess slightly so there isn't a sharp edge to catch cleaning patches. Drill the recess just deep enough to fully intersect with the flash passage from the side. I have used the Nock's breech on several rifles and it seems to work well. TOTW sells a blueprint of the design for about $2.
