Touch Hole Liner Question

[dannylj]

When you drill and tap for a touch hole liner do you not tap all the way thru the hole so the liner will have a stop? I have tapped the hole all the way thru to the bore and the liner seems loose. I thought I would be able to get one that had a shoulder on it that could be countersunk for a stop. I have several liners laying around but they are all a uniform diameter. Can I just screw it in flush and not worry about it? I hope this makes sense.  Danny

[D. Taylor Sapergia]

A touch hole or vent liner, in a perfect installation would ideally bottom in it's threaded hole at each end.  The threaded liner that has no provision for a countersink outward end and has a slot for screwing it in, is undesirable.  So buy and install a liner that will come down hard against the barrel flat, if not the bottom of the hole as well.  Usually, barrel walls are too thin now-a-days for this inward bottoming, and even must be trimmed so as not to enter the bore where they trap fowling and grab the patch from the jag.  But that is far better than the parallel sided thread that does not bottom against the barrel in a perfect countersink.

[dannylj]

I understand and totally agree with you. Having already drilled and tapped the hole, what would you suggest? I think the White Lightening liners have an outside shoulder. I could use one of those or retap for a slightly larger (5/16) liner and not quite complete the tapping to allow a tighter fit. This rifle is giving me fits.  Thanks  Danny

[Daryl]

We use only Whitelighting liners, Danny - for that outer shoulder and for their improved ignition.  They have a 32" thread, btw.  If you use one, makde certain the outer chamfer is sized properly to leavy a thick enough wall after filing off flush with the barrel.  Birchwood Casey's Plum Brown is good for re- matching your browing with repeated applications or whatever is necessary.  A variety of brown colours can be obtained. It might be best to practise on a barrel stub first.

[D. Taylor Sapergia]

I've never installed a commercial liner where the wall thickness of the barrel was thick enough to drill and tap a bottomed hole.  So i drill and tap straight through into the bore.  I want the countersink to bottom hard so that when I file the vent down to the barrel, the joint is invisible.  If you don't thread all the way through, as you run the liner in, it is going to get very tight, likely before the countersink seats.  This is going to damage the threads on the liner...sorry, I can't do that, and can't see how that's a good thing.
Some others may be able to enlighten me - - -

[Michigan Flinter]

D. Taylor use a bottoming tap to complete the job before installing the liner.

[Long John]

MuzzleLoader Builder Supply sells vent liners with 1/-28 threqads as well as 3/8-24 threads that have a countersink outboard end, both in stainless steel and Ampco.  I have used them many times.   they work fairle well but you have to adjust the length of the vent hole by deepening the counter bore or filing down the outer surface.   They are slotted for screw-driver installation.   I found that I could improve performance by custom grinding a drill bit to convert their small diamter counterbore into a true inner cone.

On my last rifle I used a White-Lightning liner by Jim Chambers' company.  They are slick!

Best Regards,

JMC

[Jim Kibler]

It's a good idea when installing one of Jim's liners to NOT tap all the way through the hole, but rather stop slightly short.  You will likely have to sneak up on the proper depth, but when completed it should tighten up at the bottom and seat on the countersink at the same time.  Jim has recommended this installation method.

[dannylj]

I appreciate all the responses. I ordered 2 stainless liners from TOW after looking at them in the catalog online. The ones I ordered showed an expanded base but when they came in they were the same diameter all of the way. I called them and they were very helpful and seemed to be surprised that those liners were still in the catalog as they are no longer available. I have not called MBS to see if they have any. May just go with Jim's White Lightening. Thanks  Danny

[Benedict]

It's a good idea when installing one of Jim's liners to NOT tap all the way through the hole, but rather stop slightly short.  You will likely have to sneak up on the proper depth, but when completed it should tighten up at the bottom and seat on the countersink at the same time.  Jim has recommended this installation method.

Jim, the kind of tap you use would make a difference here.  So do you drill all the way thru the barrel wall with the tap drill?  Then use a regular taper tap or a bottoming tap or what?

Thanks,
Bruce

[dannylj]

The hole I have already drilled and tapped for the liner is very slightly canted. This is a GM 15/16 .50 barrel. If I decide to straighten the hole and go with a 5/16th liner there will be a very small overhang of a flat. This can be easily and unnoticeably filed smooth. Anything wrong (other that aesthetics) with this?  Danny

[Jim Kibler]

It's a good idea when installing one of Jim's liners to NOT tap all the way through the hole, but rather stop slightly short.  You will likely have to sneak up on the proper depth, but when completed it should tighten up at the bottom and seat on the countersink at the same time.  Jim has recommended this installation method.

Jim, the kind of tap you use would make a difference here.  So do you drill all the way thru the barrel wall with the tap drill?  Then use a regular taper tap or a bottoming tap or what?

Thanks,
Bruce

Bruce,

Drill all the way through.  I tap with the standard taper point tap Jim provides. 

[Benedict]

thanks Jim.

What is the advantage here?  I am guessing that with the threads in the bottom not cut all the way, you will get a lot of interference.  That would keep the plug from backing out.  You also do not get the benefit of those threads holding power so there is just that much greater chance of the liner blowing out.  You still have the full diameter of the liner exposed to the pressure.

If you and Jim C both recommend this procedure, I will probably try it some time but I am trying to understand what is going on.

Thanks,
Bruce

[Jim Kibler]

Bruce,

I think the chance of the liner blowing out is nil.  I can't see the holding power of the threads being compromised much by not tapping completely through.  Keep in mind your not forcing the liner in, but rather you adjust the tapping depth so it just tightens as it bottoms on the countersink.  Your right about it tightening up well with the bit of interference.  you're not relying the small countersink alone to tighten against.  Tapping in this fashion may provide for somewhat of a better seal between the liner and bore as well.

[Benedict]

Jim,
I wasn't worried about the liner blowing out, just trying to think of all of the implications. 

You are right about a better seal.  having the bottom of the threads not filled out would do that.

I do not build guns very fast so it has been a while since I installed a liner.  It seems that every time I install one, the liner is longer than the barrel is thick.  This would mean that the liner would be going through the bottom threads.  Not what I would consider bottoming out.

Bruce

[keweenaw]

If the threaded section of the liner is longer than the thickness of the barrel you need to go in from the breech and contour the end of the liner to the barrel's inner contour otherwise cleaning is a royal pain.

Tom

[Benedict]

If the threaded section of the liner is longer than the thickness of the barrel you need to go in from the breech and contour the end of the liner to the barrel's inner contour otherwise cleaning is a royal pain.

Tom

Yes, that is what I have always done.  My question had more to do with the effects of not completely tapping the hole as suggested.

Thanks,
Bruce

[Dphariss]

If the threaded section of the liner is longer than the thickness of the barrel you need to go in from the breech and contour the end of the liner to the barrel's inner contour otherwise cleaning is a royal pain.

Tom

Its easier to just cut it before installation.

Dan

[Curt Larsen]

Someone has already mentioned this, but remember that the threads on Jim Chambers vent liners are different than some of the others.  Jime sells a drill and tap to go with his liners.  Also, I remember Hershel's method of making his own liners from existing bolts by drilling a cavity in the end of the bolt, cutting the threads up close with the die and then screwing it in to a slightly countersunk hole.  He then cut off the excess with a hack saw and filed it down flush with the barrel.  His last steps were to file off any excess inside the bore from the breech and then drill a vent hole centered on the flush head of the bolt.  Sounds a lot easier to use one of Jim Chambers' liners, but there are other ways.