Vent placement?

Does the vent placement matter as long as its in front of the breech plug “and in the power zone”?
if it does would it depend on the size of the barrel?
EG .3125” would have a different placement then .5”

i hope this is not a stupid question.

No such thing as a stupid question when it comes to vent liner placement Billy!

I never install a vent liner until my barrel is fully inlet and pinned into stock, my lock and trigger inletted and installed. I do mark the approx. location of where the liner will be (just forward of the breech plug), which is used to help determine where the lock placement goes.

Once all these things are set to their final positions, I very carefully center punch the exact spot on the barrel where the touch hole will be. One of the things I have learned over the years is to always start with the smallest T\H liner (Chambers White Lightning) 1\4". I only use the larger diameter sizes in case I run into a problem with the smaller hole drilling\threading, which has only happened to me on one occasion. The larger liners are also sometimes used (by me) for T\H replacements on worn liners and upgrades on rifles using inferior liners.

Hope this is helpful to you Billy, I wish you good luck!

Thank you!

Hi Billy,
The center of the hole should be centered on the pan and in line with the top of the pan. If you drew a straight line on the barrel across the top edges of the pan. the hole would be on that line in what some call a "sunset" position if the line represented the horizon. Hopefully your lock and pan was positioned such that the center of the pan is about 1/8" or so in front of the end of the breech plug. It is OK for the threads for the liner to invade the breech plug threads but just make sure the liner does not jam those breech plug threads.

dave

Measure twice, drill a bunch of times starting with a small bit to make sure everything is where you want it.

Thank you.
How far in the barrel can the liner extend.

This is the small cal barrel i am thinking about for a pistol.


PS Please let me know if the photo dont show...

I don't agree with drilling several times using small bits. Small bits have a tendency to walk more than larger bits even if center punched. Small bits easily bend whereas larger bits are more rigid. If you start with too small a bit and it walks a bit then each succeeding bit will be off as well. Better IMO to measure measure measure then make sure to center punch in exactly the spot required. Then using the final size drill bit start slowly and just touch the punch mark. You will know instantly if the hole is on or not. If you're off the you can move things around or center punch the direct point again without ruining things. I've drilled holes in all manner of items using this method and I rarely screw things up. The key point is to measure and center punch exactly. And always use a drill press when drilling a touch hole. If the barrel is clamped tightly to the table and the bit centered and locked the process will go straight forward without issues.

Sidney Smith said:

Small bits have a tendency to walk more than larger bits even if center punched.

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Can't disagree with you there in general. However as far as vent liner drilling, or any other critical location drilling- the proper method is to use a center drill first, which is much easier to see and adjust positioning, but eliminates the possibility of any drill wandering whatsoever.

Hi,
The liner does not extend into the barrel bore at all. To install a liner properly, you should pull the breech plug so you can see how deep the liner goes and file off any portion protruding into the barrel. You will also need to pull the plug if the liner threads intercept the plug threads.

dave

Dave is spot on... when i recently installed a liner i had to remove it several times and file it down so it didn't stick into the bore. I then used a jag and tight patch to check, and had to remove a little more metal from the liner.
Remember they make the liner so it will work on the thickest bull barrels, so I can assure you you'll have to dress it down.

Thank you all.

The way I read the original question it's asking if the vent hole or liner can be installed any place ahead of the face of the breech plug.
My answer is, that isn't a good idea.

The best location IMO is the vent should be 5/32" (.156) to no more than 7/32" (.219) ahead of the breech plug face.
Even if the vent is just a straight hole with no liner, locating it within these values will allow a 1/4" threaded vent liner to be installed later on without it interfering with the face of the breech plug.

The reason I personally don't like to put the vent further forward than 3/16" (.187) is, if a very small powder charge is loaded into the barrel I don't want to have the patched ball or base of the bullet totally covering up the vent hole.

Dave,

Do you file the liner before it's installed, or after it is in there and protruding in to the bore? If you file it once in the bore you'll probably mess up some rifling in that area, but that shouldn't matter because there's plenty of rifling left between the vent and the muzzle to catch the patch and ball.

Col. Batguano said:

Dave,

Do you file the liner before it's installed, or after it is in there and protruding in to the bore? If you file it once in the bore you'll probably mess up some rifling in that area, but that shouldn't matter because there's plenty of rifling left between the vent and the muzzle to catch the patch and ball.

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Hi Dave,
I remove the liner, file it and then reinstall to see if I removed enough. When all is good, I install the liner, crank down hard on it, and cut off the lug, then file flush. I think some folks over think this task and it does not require perfect machinist precision. After all, the gold and platinum liners installed in the 18th and early 19th centuries did not require all that precision either.

dave

I start with a 1/8" bit, never had one wander, I do have a drill press with a cross slide drill press vice and go slow, real slow. I have only put in 4 white lightning liners, all went really well.

I like that method better than what I've been doing, which is to get it sort of close, and then file it flush from the inside. I never felt that good about messing around the inside of the bore with a rat-tail file though.

Col. Batguano said:

I like that method better than what I've been doing, which is to get it sort of close, and then file it flush from the inside. I never felt that good about messing around the inside of the bore with a rat-tail file though.

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In one of Hershel Houses old videos (the ones with rooster crowing!) it shows him going in from the breech end with a steel cherry cutter held in an electric drill. Trims it flush and ads an extra bugle type flair to the liner/barrel interface- interesting.

Zonie said:

The way I read the original question it's asking if the vent hole or liner can be installed any place ahead of the face of the breech plug.
My answer is, that isn't a good idea.

The best location IMO is the vent should be 5/32" (.156) to no more than 7/32" (.219) ahead of the breech plug face.
Even if the vent is just a straight hole with no liner, locating it within these values will allow a 1/4" threaded vent liner to be installed later on without it interfering with the face of the breech plug.

The reason I personally don't like to put the vent further forward than 3/16" (.187) is, if a very small powder charge is loaded into the barrel I don't want to have the patched ball or base of the bullet totally covering up the vent hole.

Click to expand...

Yes this is the question meant to convey. Thank you. i do appreciate all the replies as i got answers to question i did not know to ask...