New to me vent liner, your opinion please

[Larry (Omaha)]

Hey Gang. I have used methods A and C, but never D which I am considering for a TH that is too high to my liking. Would appreciate opinions, but only if you have tried D or know first hand if it works equal or better than C?
Visual examination, seems like they are equal, but are they?
Thanks in advance.
Flintlocklar

 

[nhmoose]

C every time

 

[Larry Akers]

I agree, C.

 

[Grimord]

I did a hybrid of "C" & "D" on my Jaeger. I very slightly coned the touch hole on the pan side to promote better ignition. I have about .005" between the inside and outside cones. Improved ignition in this gun which had always given me a lot of FITP.

 

[dave_person]

Hi Larry,
Some of the old vent liners sold back in the 1970s and 1980s were slightly funneled on the outside as well as inside. I used them and they worked fine but the outside funnel was sometimes hard to keep clean between shots causing occasional misfires. However, theoretically, the funnel on the outside might increase the force of ignition if that occurs due to flow of hot gases rather than just radiant infrared heat. I am not clear on that last point and video research by Larry Pletcher suggests radiant heat is the culprit not a flow of gas. The outside funnel should direct and compress a greater volume of gas forcing it through the constriction and expelling it with greatly increased velocity and force. Essentially, it is an extreme convergent-divergent de Laval nozzle. When the charge blows inside the barrel, the flat hole inside would greatly restrict the volume of gas exiting the vent hole, perhaps adding force to the bullet. In the conventional installation with funnel on the inside, more gas from the charge may be funneled to the vent and expelled into the pan with greater force. Of course, that may help keep the vent hole clear for the next shot. If ignition results from radiant heat and not a jet of hot gas, then simply the distance of the burn to the charge in the barrel may be all that matters. In that case, your outside funnel would work fine but you may have created a longer distance from the heat source to the charge. Packing priming into the funnel might not help because the constricted and packed powder would burn more slowly owing to less air surrounding the grains.

dave

 

[Sidney Smith]

Is your touch hole that is too high simply a hole or is it a liner? If its the former, you should be able to center punch in the proper spot then drill a new liner sized hole that should wipe out the original touch hole. If so tnen it would be just a matter of installing a new liner as in C in your diagram.

 

[rich pierce]

As indicated above, I’d worry that while wiping the pan from time to time when things are humid, that with B or D, I’d push wet fouling into that funnel.

 

[Sidney Smith]

My Lancaster rifle has a hex head touch hole simar to that of B. Ive not had issues with fouling getting into the touch hole. Just wipe the pan away from the TH.

 

[Larry (Omaha)]

Is your touch hole that is too high simply a hole or is it a liner? If its the former, you should be able to center punch in the proper spot then drill a new liner sized hole that should wipe out the original touch hole. If so tnen it would be just a matter of installing a new liner as in C in your diagram.

Thanks for the good advice, but I never do just a vent. I always install a liner. I can plug the original hole and then re drill, but opt not to do that before trying a custom vent liner that lowers the entrance.
Larry Pletcher with www.blackpowdermag.com had this to say about vent liner D:

"If you adopt this plan you might tip the counter sink down to make the cone at the bottom more pronounced than on top. In effect you're angling the vent entrance down a bit.

A fluid dynamics guy once told me that the best way to get a gas into a hole is to use a horn shaped entrance. Remember the old hotrods with multiple carbs? They had intake shaped like horns. The idea was to cram as much air into the carb as possible. An exterior cone was my way of trying that."


Flintlocklar

 

[Larry (Omaha)]

As indicated above, I’d worry that while wiping the pan from time to time when things are humid, that with B or D, I’d push wet fouling into that funnel.

I agree Rich, but: A hole is a hole (or funnel) and when the humid prime residue gets sloppy, a hole of any type in my mind is running the possibility of getting plugged or at the very least restricted. Part of good Flintlock ignition maintenance includes keeping tabs on the TH.
Thanks
Flintlocklar

 

[Vaino]

My squirrel LR has a TH liner made from a hex SS 1/4-20 set screw and has always been reliable and "quick". The hex is towards the bbl and the TH land is 1/32 long. On both sides of the TH are {2} 45 degree slots that require a spanner wrench made from a screwdriver. The 45degree slots are in lieu of a screwdriver slot which would come across the TH. Stopped using this when I went to a Chambers' White Lightning which is just as good. The hex has never been filled w/ debris after multiple shots and wipings. My only choice of the 4 you drew is "C".....Fred

 

[Larry (Omaha)]

My squirrel LR has a TH liner made from a hex SS 1/4-20 set screw and has always been reliable and "quick". The hex is towards the bbl and the TH land is 1/32 long. On both sides of the TH are {2} 45 degree slots that require a spanner wrench made from a screwdriver. The 45degree slots are in lieu of a screwdriver slot which would come across the TH. Stopped using this when I went to a Chambers' White Lightning which is just as good. The hex has never been filled w/ debris after multiple shots and wipings. My only choice of the 4 you drew is "C".....Fred

Good idea on using a set screw, but what does the face look like relative to barrel & THL fit? Without a counter sunk ring extending beyond the THL threads I suspect there might be a slight gap. Correct me if I see this wrong because I am visualizing and not actually seeing one.
Thanks for sharing!
Flintlocklar

 

[Vaino]

The set screw end doesn't go as far as the bore.... it's stopped short of the bore by not running the tap through to the bore producing tapered, shallow threads. I don't have to do this w/ the White Lightnng because a ctsk head stops the liner. Some contour the end of the White Lightning so it matches the bore.....I don't do this and just recess the end of the liner......Fred

 

[Larry Pletcher]

I'd like to slightly modify my this quote with the complete paragraph for my earlier email advice.

Larry Pletcher with www.blackpowdermag.com had this to say about vent liner D:
"If you adopt this plan you might tip the counter sink down to make the cone at the bottom more pronounced than on top. In effect you're angling the vent entrance down a bit.

Here is the complete paragraph:
I'm currently using Chambers liners that is similar to C but the inside is a bell shape. I also like to add a tiny cone to the outside. I spin a counter sink trying to remove any sharp edge of burr in the hole. I spin the counter sink by hand. Recently I like to take a little more off, leaving a very small cone around the hole. This cone is limited by how thin the web is when the liner is installed.
If you adopt this plan you might tip the counter sink down to make the cone at the bottom more pronounced than on top. In effect you're angling the vent entrance down a bit.

The issue is that I do not use a TL like "D". The description refers to a slight exterior coning to a Chambers liner instead (more like C). I do like the bell shape of the interior on a Chambers Liner. I have no test results that prove this; just my gut talking out loud.
Regards,
Pletch
PS: I hope this correction makes sense.

 

[flntlokr]

My squirrel LR has a TH liner made from a hex SS 1/4-20 set screw and has always been reliable and "quick". The hex is towards the bbl and the TH land is 1/32 long. On both sides of the TH are {2} 45 degree slots that require a spanner wrench made from a screwdriver. The 45degree slots are in lieu of a screwdriver slot which would come across the TH. Stopped using this when I went to a Chambers' White Lightning which is just as good. The hex has never been filled w/ debris after multiple shots and wipings. My only choice of the 4 you drew is "C".....Fred

View attachment 46652

exactly what I make; I also stick a counter sink into the inner hole to make a venturi, leaving a very narrow shoulder.

 

[Intosomthin]

I got a nwtg as no liner straight drilled 5/64th, as well as a 45 penn rifle, converted cap to flint, no inner or outter cones. They fire 100% of the time if pan flashes... now getting pan to flash as you all know is NOT 100%. But i always run pick in flash hole after loaded, prior to priming. Clear path for flash. If prime flashes theres damn lil gap in trigger/ fire time. The 45 is instant... Back to point..niether gun coned inner or outter...stright 5/64 hole?

 

[Larry (Omaha)]

I got a nwtg as no liner straight drilled 5/64th, as well as a 45 penn rifle, converted cap to flint, no inner or outter cones. They fire 100% of the time if pan flashes... now getting pan to flash as you all know is NOT 100%. But i always run pick in flash hole after loaded, prior to priming. Clear path for flash. If prime flashes theres damn lil gap in trigger/ fire time. The 45 is instant... Back to point..niether gun coned inner or outter...stright 5/64 hole?

Thanks for the reply. I don't believe the early flintlock makers even knew what a conned vent was. Sure, a straight vent works, it should, if the powder and spark are there. The question I ask you is this: Is it faster than a conned vent? A few milliseconds faster makes a big difference for me.
Flintlocklar

 

[Vaino]

Just guessing, but seeing TH liners weren't used back then, I don't think a plain, drilled TH was .062 dia....probably a lot larger and definitely a lot larger if a thick walled bbl was used. .....Fred

 

[Pete G]

The gun shop at Colonial Williamsberg has an original tool for coning the inside of a vent.

 

[flntlokr]

Coning the vent hole creates a venturi effect which increases the speed and pressure of the explosive wave. That will have some effect on what happens with the flash, and probably increases its effectiveness in squirting the flame deeper into the main charge. Some bright soul could probably figure out some way to measure that effect. I figure that if the Old Boys (who had to make a living with their guns), took the time to do it; there was most likely a good and tangible reason. So I cone my liners, leaving the shortest throat I can. Works for me.