Vent re-do?

[CWC]

I finished my .54 Chambers early Lancaster kit about 6 months ago. I don't have a drill press, so all the drilling was free-hand with a cordless drill. I had decided to use a simple 1/16th inch drilled vent, no liner, since that was the most common original method. Well, I messed up with the drilling. Must not have center punched my spot too well, because the hole wandered a bit lower than I wanted. That's not the worst part. My free-handed hole also ended up being angled slightly down. I ended up with a fairly noticeable hang fire.

Is there any thing I can do to fix it? I thought about just drilling it out a little bigger, tapping it, installing a permanent plug, and then trying the drilling operation all over. Would there be any problems with this?

 

[bennypapa]

I'd install a White lightning touch hole liner, but not with your tools. Now that you have an off-center hole that is also off axis you may have to use some sort of bushing to get back on track. Otherwise any further drilling may try to follow the existing hole.

It may be time to seek out the local machinist or send your barrel to a qualified smith to have the touch hole liner installed.

 

[Vaino]

I'd go to somebody that has a milling machine so an end mill could be used which would relocate a hole for a liner. You then could tap the hole or have the machinist do it. Drilling any further w/ what you/ve got could really make things a lot worse. Remove the BPlug before milling the hole. I use "White Lightning" TH liners and they yield reliable, fast ignition..Good Luck....Fred

 

[RwBeV]

Pt sent

 

[jsn]

I had something like this happen on a lock I was building. all I did was tap it for a small bolt then screwed it in and tightened it down cut it off an filed flush after peening then I re located position and re bored and tapped. you could probably get by with just mashing a soft metal into the surface to getit back on track but ive not been doing this kinda stuff as long as these guys, theve probably been messing with the stuff longer than I've been alive :bow:

 

[Denny/Oh]

Gotta agree with Flehto. Its a relatively easy fix this way and if you provide the W/L tap its all the same setup.

Explain the problem to the machinist and let him know exactly what you want and it should come out OK. I've done a couple of these repairs with good results.

Good luck.

 

[tg]

If not yet done the first thing I would do is to cone the inside of the hole a bit and enlarge the hole a drill size larger. I use 5/64 or a size smaller holes with no liner and they work fine on the larger bore guns .54 and up, I think you can solve this with out reverting to a liner, most are surprised at how well a plain hole can work, there is some info somewhere on the forum for making a an inside coning tool out of a finish nail.Remove the plug and determine just how much of a downward angle tou aredealing with and where the hole is in relationship to the breech plug face, historiicaly and presentl;y the plug face was/is relived a bit for a clear flash channel, I would just not start going forward with a liner until other things have been examined. elininated as the problem.

 

[CWC]

TG, thanks for the idea. I already coned the inside, using a round grinding bit on a dremel. I did the coning before I ever shot it, so I couldn't compare how much of a difference it made. As for enlarging the hole slightly, that's a good idea, and it sure couldn't hurt. If I decide to tap and thread the hole I'll have to enlarge it anyway.

 

[Zonie]

You said the drill wandered a bit and ended up lower than you wanted it. You didn't say how much lower and that does have some bearing on the answer.

You also said the hole ended up at an angle that was slightly downward. Again, this will have something to do with a good answer.

If the mouth of the hole is a little low but it is above the bottom of the pan it should not cause a significant problem with ignition.

What might be causing the slow/hang fires is the size of the hole.

As you may have noticed, most of the vent liners used work so well because they are relieved or hollowed out on the inside. This places the powder charge within 1/16" of the outside of the barrel and a 1/16" diameter touch hole presents a goodly amount of powder directly to the blast from the pans flash.

With your non-liner hole the barrel wall is at least .200 thick and because the inside of the hole is not relieved the powder from the main charge is also at least .200 from the pans flash.

Add to this the fact that as the pans flash travels thru that 1/16" diameter X .200+" long hole it is rapidly loosing heat to the walls of the hole.
Combining these two things it is little wonder that the ignition is erratic.

To fix this condition my first recommendation would be to enlarge the holes size to 5/64" and try the gun. It should show significant improvement.

If it still isn't living up to your expectations the only easy fix is to replace the hole with a vent.
Here is where things can get sticky because the liners tap drill will want to follow the existing touch hole.

If the height of the hole isn't more than 1/32 below the upper surface of the pan then it would still be OK for a liner. If it is 1/16 below the top of the pan you will have to use your own judgment.

Before thinking of a liner you will also have to measure the center of the touch hole to the face of the breech plug. Do this by running a rod down the bore and by making a mark that is flush with the muzzle on the rod. Then, hold the rod along side the barrel aligning the muzzle mark and notice where the touch hole is relative to the end of the barrel. If the distance is more than 3/16" your good to go with a 5/16" or 3/8" liner.

If the distance is greater than 1/8" you can use a 1/4-28 liner which some folks think looks better.

Now you will have to decide if the angle of the existing hole will cause a problem with the threads for the liner.
If the angle will not cause the tap to run into the bottom of the barrel you should not have a problem.

If no potential problem exists then use the correct tap drill and tap to create the new threads for your liner.
After it is installed you will need to file the outer face of the liner flush with the flat on your barrel but that shouldn't be a big deal provided you protect the adjacent areas with masking tape or something similar to protect the browning from the file.

If the fore/aft, up/down or angle is going to cause a problem with a threaded liner you will have to have the new liners threads drilled in the "correct place" and at the correct angle.
This is why the other folks are talking about using a milling machine to redrill the hole for the threaded liner.
Only a milling machine has the rigid strength needed to keep the new hole where it is supposed to be because, as I mentioned, the tap drill will try to follow the existing hole.

Let us know what you decide and how things work out.

 

[tg]

"As for enlarging the hole slightly, that's a good idea"

It is worth try I find a hole with no liner much to my liking, it gives one a much closer experience to doing things the way they used to be done, which for me is a big part of the game, if the ignition is a bit slower a more steady hold might be the answer :idunno: after all it worked for over 200 years in the past without having to have liners on all new guns, probably only on a small percentage of them, likely mostly Ruro guns I suspect.