Lock Bolt through Tang? Breech Plug distance to pan?

[vette_lover2004]

As some of you here know, I'm in the early stages of assembling/building a Chambers New England fowling piece.

Today I spent an honest three hours slowly scraping black spots away from the wood...and something caught my curiosity. All Chambers kits are pre-inletted, and I noticed that where the barrel placement will be to the lock, sets the pan about 1/4" from the breech. Granted, this is preliminary, but seems like a pretty good amount. I was forced to get the breech as far back as it is because the wood was gouged somehow from the router/duplicator process. So, I started squaring the breech to this point and have started inletting the barrel, while carefully keeping tabs on flash pan position.

I really have no sort of movement room fore or aft on anything, so I have to make things look real pretty where they are :hmm:

Secondly, as I was sort of mocking parts, I had the side plate lined up to it's pre-inlet spot, and where the lock bolt would go through, it would just barely touch the breech tang. Basically I would rat tail file a half round for pass through but not a complete hole if all lines up in this way. My question is this: Does the lock bolt have to go through the breech tang or can I have a half round cut into it and the bolt be supportive BEHIND the tang, while essentially locking the tang in place

 

[54ball]

sets the pan about 1/4" from the breech.

1/4" from the breech end of the barrel of the barrel or 1/4" from the breech plug face?

All the lock nails do is hold the lock on. The tang bolt holds the barrel. The half hole will be fine through the breech lug. It can be tight but you need to make oversize so the lock bolt "nail" can pass easily though. If it's too tight and say you have it out in damp weather it can rust and bond to the tang lug.

If you have to make a half round hole in your tang lug " breech plug" do not drill it in the stock. Especially on a half hole the bit can grab or slip possibly damaging the stock. So I would drill through the stock for my lock nails with out the barrel or tang in the stock. Then I would install the barrel mark where I need to drill the lug remove and drill it in a press or even file a half round hole.

 

[Vaino]

To begin w/....what reference books do you have?

Also, did you mark the plug face on the side of the bbl as reference when seating the breech and depending on the TH liner size, layout the correct centerline for the liner? This centerline is determined by half the liner dia. plus a 1/32" ahead of the plug face. The liner centerline then is centered w/ the pan when seating the bbl breech end.

No big deal on where the rear lockbolt goes through the breechplug bolster. As was said, if the hole isn't completely inside the bollster, then a groove has to be filed in the rear of the bolster.

From your description and terminology, can't determine where your TH is located.....Fred

 

[Keb]

I was taught the rule for threads is depth = diameter. In other words, 5/8" diameter should be 5/8" deep. I was also told the fence on the pan should line up with the end of the barrel. I know you can find some that it doesn't but this is the case in the majority of original guns. Most Chambers locks I've dealt with have a nice big pan and the fence is back far enough to line up with the breech end of the barrel. The Siler is the exception. So, if you have a 5/8" diameter breech plug thread that is 5/8" deep, the center of the touch hole should be at least 5/8" from the end of the barrel and have the touch hole come out in front of the plug's face. It may not though, depending on the lock and where the center of the pan is located.

If you are putting together a 95% inletted kit, you pretty much are limited to where everything goes.

It doesn't really matter where the rear lock screw passes through the plug bolster as long as it hits the meaty part of the lock bolster. There is nothing wrong with just filing clearance for the screw.

 

[jdkerstetter]

I was taught the rule for threads is depth = diameter. In other words, 5/8" diameter should be 5/8" deep....

Hey Keb, While a good rule of thumb, using a plug that is as long as it is wide is not necessary and would complicate gun building.

There are many factors that engineers take into account when figuring necessary thread engagement and it is not necessary that a 3/4" plug be 3/4" long to be safe. Where would your lock fence be on a large bore fowler with a 7/8" plug that was threaded 7/8" into the barrel?

I won't belabor the point, but plugs are not nuts and bolts. :wink: Enjoy, J.D.

 

[Vaino]

Rice bbls have a 1/2" long threaded plug for the 5/8 threads and that's one reason I buy their bbls. Having the threaded length equal to the dia. would result in an awkward architecture using a 5/8 or 3/4 threaded plug. Many originals don't have the fence lined up w/ the breech end and some stock protrusion behind the fence can be seen and there's nothing wrong w/ doing that today. Actually, depending on the lock, the longer the threaded length, the further the fence is from the breech end.

Actually I would prefer a shorter threaded length for the plug, say 7/16" and it would be just as safe.......Fred

 

[rich pierce]

Kits are devilish things sometimes. Harder to build than from a blank. Easier to shape, harder to build. I hate that sideplates are inlet at all. Same for locks.

 

[vette_lover2004]

1/4" from the breech plug face...I laid it up on the barrel and marked it with fine permanent marker to show where the plug ended...so when I laid the pan up on the bolster to gauge where it was going to be for pan placement, I saw that it was that far forward of the breech plug face.

As an aside, just so everyone knows, I'm not installing a vent liner. I have one of Thomas Snyder's touch hole counter bore tools. If you aren't familiar with this tool, it effectively does what a white lightning does without taking away from an authentic look. Which, is what I'm trying to accomplish for myself with this piece.

Lastly, my references are a DVD from James Turpin on how to build the chambers kits, and the book, "The Art of Building the Pennsylvania Longrifle". But, I do want other references like "Grenville" and the like. I've been trying to find the book on fowling pieces specifically but it seems to be out of print and folks want an arm and a leg for it. :td:

 

[vette_lover2004]

This is my first build ever... So I really cant comment. But, I do wish they hadn't done either as well. I have a general idea of how things should look, as I held a built kit done by Mark Silver himself and talked with the chambers clan on how to build their guns in person. You can only gather so much information in a short window of opportunity, unfortunately. I do know the breech plug is prefitted and is exactly .504" in length, and is exactly .871" or approximately 7/8" in diameter. Its pretty darn beefy to say the least. It is a 12 bore Rayl barrel.

 

[vette_lover2004]

The fence...that's the rear of the pan that kicks up and just barely misses a released cock? Upon inspection of the pan... It does look like there is some meat on the rear side of it near the fence. Can this be removed some to allow for more movement fore or aft for better touch hole placement?

 

[Keb]

I was taught the rule for threads is depth = diameter. In other words, 5/8" diameter should be 5/8" deep. I was also told the fence on the pan should line up with the end of the barrel....

I guess I didn't clarify. I was taught in my trade (not making muzzleloading guns) diameter = depth. Having the fence line up with the back of the barrel certainly won't work most of the time. Sorry for the confusion.

Also, I know there are original guns have the pan forward of the end of the barrel. I have had that pointed out to me every time I mention the fact that many originals lined the pan with the end. I was also told this many years ago when I 1st started fooling around with these things. I only wish my memory was good enough to actually quote it.

 

[54ball]

OK
So if I understand right the center of your pan will be 1/4 inch in front of the breech plug face, correct?

Ideally you should be about 1/8 or so in front of the plug face. If you were using the 3/8 white lightening liner you would only be off by a 16th.

So IMHO you are good to go. The fence of the pan may be forward a little more but the gun should function fine and as said many original pan fences were ahead of the breech. So again I think you're fine. :thumbsup:

Now if you wanted that 1/8 back you could always glue a piece of well matched maple a little bigger than 1/8 to allow fitting and re fit the breech again. But like I said I think you are close enough.

Since the lock inlet is smaller than the lock you may can ease the lock back just a hair closer to the breech and still be in the inlet.

 

[Zonie]

IMO, if the face of the breech plug is 1/4 inch behind the center of the pan when the rear of the barrel is firmly against the rear of the barrel channel, things will be fine.

I think Chambers did that because almost everyone installs a vent liner and a 1/4" distance will easily accomodate the threads on the liners he offers.

If the gun isn't going to use a vent liner and it is going to have a simple vent hole drilled, that's not too bad either.
In a .54 caliber bore a powder load of 25 grains will stand about 7/16" high.
A load of 20 grains will stand about 3/8 inches high.

In a .45 caliber barrel a powder load of 40 grains will stand about 1 inch tall.
A 20 grain powder load will stand 1/2" high.

I mention this because if there is a fear of the patched ball blocking off the vent hole with light powder loads you can see that for any practical load, there isn't a problem.

 

[vette_lover2004]

Yes exactly...the center of the pan will be 1/4" from the breech face...ill try and inlet the lock as far back as allowable...but im not that far yet. I just wanted to make sure i wasnt painting myself into a corner, when i didnt lay out the plan...well good to know on both counts that i should be okay...so far its been so much fun that i think sbout it at work...lol

 

[54ball]

There's a lot more to it than you thought isn't there?

 

[jdkerstetter]

This is why it's so vitally important to inspect everything upon arrival, prior to doing any work on a stock or metal parts.

You indicated above that the wood at the breech was "gouged" by the router/shaper so you had to set the barrel back farther than intended. Had this been addressed soon after you received it, Chambers could have corrected the problem.

All that being said, I have measured several guns, to include my own and builds completed by 3 other builders, and the vent hole on each is roughly 7/8" from the end of the barrel, some less, none more.

So, I don't believe 3/4" is a deal breaker, especially since, you indicate that this is a fowler build I assume you are using one of Chambers BIG locks.

Procede and Enjoy the Journey, J.D.

 

[vette_lover2004]

I did inspect the wood when I first got it. I assumed the small gouge was of no concern because I was going to be working that area anyway. It was only when I started to get the barrel set into the wood that I made this discovery as I was trying to make sure everything was lining up properly. I was trying to cover all my bases as I was working the wood. It was only when the barrel had finally sat down in the channel and the breech was nearly square that I got a true sense of what was going on. Yes, everything in the kit is Chambers except the barrel which is a Rayl.

As to 54ball...No, it wasn't more work than I expected. I had spoke with the Chambers clan in emails and in person, as well as research the building of kits, and started reading my book I purchased. I had the build DVD two months in advance. I had watched that three times, and all of duelist1954 youtube videos. So, I was well prepared for the time (probably a year), money (well over a grand), and labor (this is a bonus to me)involved in such a project. I dont go into a project without first doing deep research. And I got this kit for a few reasons. To learn new skills, and enjoy a new aspect of the firearms hobby. And the fowling piece has signifigance to me because of its immense role to the colonists during the Rev war and my love affair with the shotgun. They were and still are so versatile as a tool.

 

[vette_lover2004]

Almost forgot...the lock is a Chambers Colonial Virginia...one of their biggest locks I think.