Touch Hole Liners?

[Don B]

It's possible to get a Chambers liner made of steel and they don't show as much as the non-ferrous alloy ones. They are machined from the same free machining leaded steel many barrel makers use, I think.

In recent conversation, Jim Chambers recommended the leaded steel liner only for exhibition guns, since the liner's thin land would erode very quickly (only a few hundred shots). He also said he thought Birchwood Casey makes a solution that will brown stainless steel, and so would help hide the SST liner.

Don

 

[Dphar]

A *good* vent liner design, *properly installed* (the details of this process alone can provoke "debate") increases ignition speed and reliability.
If the diameter is too large for the barrel it can weaken the breech. If poorly installed it could leak gas past the threads or even blow out.
If you want an absolutely "authentic" Kentucky you can use either a plain vent or a "bushed" one and be safe. Bushing vents in rifles is documented to F&I war times in America. Though stainless "bushings" are a little too new.
The guns purpose is another guideline. If its used mostly as a prop for re-enactments its different than if you hunt in the woods with G-Bears that have learned that a gunshot is a dinner bell. In the latter case reliability becomes more important.

Dan

 

[Dphar]

In a private thread someone mentioned that he believes the parabolic cone of the white lightening liner provides a thermodynamic effect (in addition to bringing the main charge powder close to the pan). Very interesting perspective. If I get a chance I'll have to ask one of the mechanical engineers here at work about it and see what they think...

I believe that the distance from the priming in the pan to the powder in the vent is key. A small diameter liner 10x32 with a .100" counter bore on the inside is nearly as fast as a 1/4" WL in the same barrel. The WL undoubtedly spreads the flame faster once ignition takes place.
The WL is not a "new" design. It appears in drawings of British breeches of 1780s-1790s.
It is an EXCELLENT design and Jim Chambers should be commended for offering it. Fast and sure fire.
I have a lathe and access to many feet of otherwise scrap 5/16 303/304 stainless rod so while I have used them I tend to make my own. Design depending on the use its to be put to.
Shooters and builders should also note that fire does NOT enter the vent to any extent, the pressure wave is not that strong. The ignition is generally by RADIANT heat to the powder that can "see" the flash through the vent.
In a properly made vent the distance from the prime to the main charge in the vent should not exceed .040" or so. With a .060" diameter vent and a proper counter bore for the granulation used the powder will be *right at* the pan/barrel interface.
The English worked for decades starting in the mid 18th century to speed flintlock ignition for wing shooting. They patented all sorts of stuff, by about 1800 the English flintlock as made for high quality guns was unsurpassed for speed and reliability. The locks were fast, the vents were fast and it was all for wing shooting. Rifle use was secondary.
Larry Pletcher (Blackpowdermag)has been working on timing flintlocks and vents and has produced some very good data. Testing is ongoing.

Dan