advice on touch hole position

[kswan]

Hello Fellows.

This is something I should have noticed when I started this build. The Touch hole is sitting quite high, above the frizzen when its closed. The kits came pre inletted and the lock, tang and stock drilled. I measured and the hole has been drilled in the barrel a bit to high. I notice from measuring from the top of the barrel to the stock the rear of the barrel sits higher on the last 5 inches than the rest of the barrel. Should I look at a new barrel properly drilled or try to inlet the rear of the barrel to bring down the TH?
Picture to follow.

Thanks.

 

[LRB]

A picture would help. Even an accurate diagram. What kit is this?

 

[kswan]

Late Lancaster. I having internet problems on my end. This is going to be slow.

 

[kswan]

 

[Vaino]

Is it a used bbl or did you tell the supplier to install the TH liner? It's too high for the lock location and doesn't look centered vertically on the bbl flat.....the upper edge of the liner is nearly touching the corner. Again that's the reason for asking if it's a used bbl.....I install the TH liners on my Bucks County LRs that high and the liner is the last thing I do before browning. The locks are also inletted very high.

Are you positive the bottom bbl flat is against the bottom flat of the bbl inlet? Are you using a spotting agent to ensure that it is when lightly clamping the bbl and stock? If the breechplug is inletted, is it interfering w/ bottoming out the bbl?

Is this a kit from a supplier or is it a bunch of parts purchased separately? Seems so.

Whose kit is it if indeed it is a kit?.....Fred

 

[rich pierce]

Fred's got it covered but I will ask a couple things too.

Is it a touch hole or a liner? If a touch hole just drilled you an plug that hole and drill it in the right location for a liner.

Is there anything preventing you from inletting the rear of the barrel 1/8" deeper? If already drilled for underlugs pins forget that. How thick is the web at the front lock bolt hole?

 

[Zonie]

If the hole is covered by the frizzen when the frizzen is closed, you can leave it alone.

Even though it is high, it will still work.

If closing the frizzen does not cover the hole you have a couple of options assuming that the slotted looking thing is the slot for a vent liner.

You can remove the existing liner and buy a stainless steel bolt with the same thread as the thread on the liner.

Cutting off a length of the bolt to the same length as the existing liner and adding a small slot to allow you to screw it into the barrel you can then reinstall the barrel, mark the touch hole position in the right location, and then drill a new hole in the corrected place.

That would be less work than the other option which you mentioned.
That option is to try to inlet the barrel deeper into the stock.

Before taking this option, note the amount of wood that will need to come off of the wrist of the gun to match the lower barrel position.

If it is around 1/8" that might weaken the wrist more than one would like.

It might be best to find out how far down the barrel needs to move to get the frizzen to cover the vent hole. Then, remove the wood to move the barrel down just a little bit more than that without trying to get the vent down to the "optimum" location.

 

[Col. Batguano]

It looks like a liner to me. I wonder if it'd be possible to take the liner out, install a plug in place of the liner, and re-drill a new liner in the correct location?

I did that with a lock bolt I mistakenly drilled and tapped for a #10 bolt when it should have been a #8 once. Just screwed in a #10, cut it off, peened it, filed it, and re-drilled and tapped in the same place for a # 8. No problem, You really can't see it now unless you really look for it, but that's not the same thing as a vent liner in a high pressure area like the vent.

If you just decide to live with it and soldier on, the gun may still work, but my hunch is that your ignition probably won't be as reliable as if it were in the proper place to start with.

Drill bit "walking" like this is bane and source of many of these problems, though not always to that degree. Try using center-pointed drill bits for some of these holes in the future. They can cure a lot of it.

 

[excess650]

If the rear of that barrel is higher than the rest, pull the breechplug and see if the barrel will drop further into the stock.

 

[kswan]

Thanks everyone one for the good advice. It is a complete kit, the barrel already had a touch hole liner installed. It is bottomed out using spotting agent. I dont think I can go any deeper as I would have to somehow re drill and move the rear lock bolt down 1/8th or so. I think someone asked, the frzzen does not cover the TH when closed.

 

[Vaino]

Your kit has the first TH liner installed on a kit that I know of. I still think that the bbl was a reclaim from another MLer.....unless you requested that the TH liner be installed.

Probably the easiest fix is to screw in a SS blank liner and redrill the TH. A SS bolt or screw would be the blank.

What is the bbl dim or dim across the bbl flat?? If it's large enough, the liner hole could be cut larger in a mill seeing the liner is close to the corner and could be shifted downward, tapped and ready for a new liner.

What is still puzzling is that a TH liner would be installed on a kit bbl.....Fred

 

[excess650]

If the TH is exposed with the pan closed, its TOO HIGH. Whoever installed the liner made a mistake.

There is no reason to relocate the lock bolt. The idea was to lower the barrel into the stock to bring the TH in better relationship to the pan. If the barrel can't be lowered, then move on to either Fred or Zonie's suggestions. Plug and redrill, or use and endmill to bore the hole eccentric and switch to 3/8" liner.

If the barrel was already inlet, lock inlet, and liner installed as a kit, the supplier of the kit should be solving this problem, as in supplying a new barrel.

 

[ApprenticeBuilder]

I would think that at this point, if you cannot return the kit,

I would re-inlet the barrel until it's deep enough for the touch hole to work, I would tap the existing hole in the breach plug and install and peen a threaded plug then re-drill the breach plug as needed. Otherwise you have a very unsafe condition there.

This will also aid in thinning the overall profile as well

 

[kswan]

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Attached is a close up of the TH. You are right, I dont think its a liner. From my novice point of view it looked like it was screwed in.The dark marks on the bottom are penciled in position of the pan. The kit came from TVM. Im sure they would fix the problem but shipping cost to Canada is outrageous.This then could be just a matter of installing a liner in the proper position. I really dont want to inlet the barrel deeper as the pre exsiting hole drilled in the barrel plug probably contact the new hole.

 

[Tinker2]

Looks like a liner to me.

Send it back or take it to a good gunsmith.
If you send it back you should not be the one that pays the postage.


William

 

[bpd303]

Yep... looks like a liner to me that the TH has been drilled off center. Like Zonie said pull that liner, install a blank and drill it in the proper position.

 

[Zonie]

Touch hole liners are threaded steel plugs that are screwed into the barrel.

From the factory, they come with the vent hole pre drilled and often have a hollow relief on the end that goes into the barrel. The relief brings the powder closer to the outside of the liner to improve ignition.

Touch hole liners often have a screw driver slot or a hexagon hole formed into the outside to allow installation and in your guns case, removal.

You need to remove the existing liner and find a stainless steel screw with the same thread size as the existing liner.
Most likely, the thread size will be 5/16-24 UNF although it is possibly a 1/4-28 UNF.

Stainless bolts or set screws are commonly available in both sizes.

As I suggested before, after screwing the new undrilled plug into the hole in the barrel and filing the exposed end so that it is flush with the existing barrel flat, install the barrel into the gun.

Open the frizzen and determine where the upper face of the pan is.

Scribe a horizontal line on the new liner at the same height as the top of the pan and scribe a vertical line at the center of the plug.
(It is possible that the new location is too close to the lower area of threads to use as a location for your new vent hole.
If this is the case, scribe the line just a little bit above the top surface of the pan. 1/16" should be all right.)

Use a sharpened nail set or a sharpened nail and a small hammer to make an indentation at the intersection of the scribbed lines.

Drill a 1/16" hole thru the new plug using the indentation to position the drill bit.
Use almost no pressure on the drill when you start drilling.
After the drill has gone about 1/16" deep you can increase the pressure but not by too much.
These little drill bits are very easy to break. (You might want to buy several.)

 

[Vaino]

Also get rid of that large radius at the juncture of the breechplug bolster and bottom side of the tang.

There's a flat behind the breech end of the bbl that can be eliminated if the radius is gone.....the downward slope of the wrist should start right behind the breech end....Fred

 

[Trot]

It looks like the problem is twofold. It appears like the lock is too low in relation to the barrel as well as the touch hole too high.

 

[kswan]

I think the best bet is the contact TVM tomorrow and start from there. Thanks all for the advice.