need help with lock placement!!

[Dphariss]

Dan Phariss,  The discussion about fence placement gave me pause.  If your breech plug is .50" and the 5/16" diameter white lightening vent liner is used that adds another .156" to vent location.  I measured the two locks I have here, a Ditchburn and a Chambers Golden Age for the distance from center of pan to back of fence.  They are strangely identical at .437".  Therefore the fence is going to fall .119" inch forward of the end of the barrel.  But even if I were to use a simple drilled vent w/o liner the fence would never be at the rear of the barrel.  So the question is what in your opinion is an acceptable amount the fence could be forward and be acceptable? 

Dr. Boone, you showed two different locks in your photos.  The one has the fence substantially forward of the end of the barrel and the other does not.  That second lock obviously has much greater space from the center line of the pan to the backside of the fence.  I have wondered why, since the use of vent liners is so popular, why lock makers haven't lengthened this dimension in order to accommodate fence and touchhole placement. 

First I don't use 5/16 vent liners in barrels. You will not I stated a .100 hole. A hole over about .110" moves the center too far forward. The large coned vents will move it even farther forward.
Second I like the fence at the breech of the barrel. If its much more than 1/8 then you have to figure out if you are going to leave a finger of wood running forward to the back of the fence or not. I think this looks like $#@* if more than 1/8" or so. If it runs past 3/16 it just gets worse. But many precaves have this built in.
If you have a breech plug that requires the vent to be too far up the barrel use this.

About flush

Inside the barrel.  12x32 liner sealed against a shoulder and part of the breech plug. The breech plug is sealed to the bore so there is no leakage to any threads


A little forward


Don King Pistol

Don King rifle


Two views of a rifle built on a precarve. I think the lock is too far forward or the barrel too far back maybe a little of both. I don't like the little sliver of wood running to the fence.


Its a great rifle and the owner really likes it. But it would look better with the fence at the breech of the barrel or within an 1/8" or so.

I would also point out that on PISTOLS its sometimes necessary to set the lock at a place that allows the grip, the trigger and lock to all work together and give the best fit in the stock. I moved the lock in the second photo around trying to get the trigger in the right place, the lock in the right place so as to give the proper reach to the trigger and get the lock so it fit the curve of the stock right.
I breeched both pistols and both have 1/2" or a little more breech plugs.

This is another answer to vent location.

This actually works very well in all regards.

If you start messing around with the locks then the locks look strange.
The question I have is why are some barrels tapped so deep for the breech?

Dan

[Jerry V Lape]

Dan,

Once again, thanks for the assistance/explanation.  I agree the fence looks much better aligned with the rear of the barrel.  And I really like the idea of the recessed breech face per your last diagram.  (I have trouble interpreting the photo of the breech with the connecting seal ).  I am going to have to get some help with machining of the breech plug and try the recesses arrangement in the next build.

[Don Getz]

There is no hard and fast rule that the fence is to be even with the breech end of the barrel.   As for that little piece of
wood behind the fence if the lock is moved forward, I had a mild argument with Allen Martin on this subject.   Allen said,
go check the RCA books.   Sure enough, most of the rifles don't have that little extension of wood behind the fence, it is
cut off clean in alignment with the breech end of the barrel, leaving a gap on those guns where the lock is forward on the
barrel.   As for lock placement on those old guns, remember, they did not use touchhole liners, just had a drilled hole in the barrel..............Don

[Rasch Chronicles]

Fellows,

What a great discussion! Learned quite a bit.

Best Regards,
Albert “Afghanus” Rasch
The Rasch Outdoor Chronicles™
Custom Gunsmith Student, J Chan Interview

[A.Merrill]

 graybeard, thanks for the reply. I knew somebody had to have done some test of some kind on breach plugs length. I think I will stay with 1/2in. for now.    AL         

[greybeard]

Al;   1/2 is plenty. 5/8 is overkill.   I think a plug 7/16 woud be fine and with a 12+32 or 10/32  liner just in front of the plug the fence should be right on at the back of the fence .  I personally refuse to drill anythibg that is going to intercept the plug threads.. Course these are only opinions.   Bob

[A.Merrill]

    graybeard, I know a guy can't always get the fence and rear of the barrel to line up, but it does look better when they do or close anyway. In the first pic Dphariss posted it just looks allot better lined up, don't you think so? Oh, by the way, good luck on the one your working on. I been keeping an eye on it.     AL

[Dphariss]

Al;   1/2 is plenty. 5/8 is overkill.   I think a plug 7/16 woud be fine and with a 12+32 or 10/32  liner just in front of the plug the fence should be right on at the back of the fence .  I personally refuse to drill anythibg that is going to intercept the plug threads.. Course these are only opinions.   Bob

In the drawing the threads are all sealed from powder gases. Its a non-issue. Nor is there any reason to pull the breech. Loading without powder is easily fixed by trickling powder through the vent. The ball cannot enter the "cup" since its slightly under bore size.
Even the bore scope photo in the previous post while its right at the breech face all the threads are sealed. The mark on the breech face is from the pilot drill and the hole entering the bore is only about as wide as the land. The liner is 12-32 shouldered at BOTH ends of the threads.
But it IS necessary to do all the breech plug and liner fitting in shop.
Fitting  vent liner as pictured, either in the side of the barrel or into the breech as shown also greatly reduces the pressure on the vent threads.

If you are buying breeched barrels for builds its very possible they do not have a good seal at the end of the bore and this is a far greater concern for safety, ease of cleaning and reliability than seating the liner as shown in the drawing.

This is the breech face of a "breeched by the maker" barrel.

Its possible to see the threads behind the grooves since the breech is machined like this.


Which results in a fouling trap like this.


Barrels I breech do not suffer from this problem.
Dan

[greybeard]

    graybeard, I know a guy can't always get the fence and rear of the barrel to line up, but it does look better when they do or close anyway. In the first pic Dphariss posted it just looks allot better lined up, don't you think so? Oh, by the way, good luck on the one your working on. I been keeping an eye on it.     AL

Thanks Al; very slow going on the Berks gun In the pic you can see the lock is stillma bit too far foreward and thats with a 10/32 liner .

[A.Merrill]

    graybeard, look at the Don King rifle Dphariss posted here. It looks to have the same amount of wood left as yours and it looks good. Better than a big tit of wood or a gap. Your gun is coming along great buddy, love the wide curl in it.    AL

[Blacksmoke]

I am with Dan in regards to your lock fence being back against the breech line.  Just because an old timer gunmaker did it different does not make it  correct or acceptable at least in my shop!  The drawing that Dan posted is the way I have been breeching for 30 yrs. and it is a proven method and the most strong of all breeching methods.     It also puts the ignition at the back of the charge instead of at the side of the charge.  I believe this makes for a more efficient burn of your powder and subsequently a more consistant burn shot after shot.   Hugh Toenjes

[Jerry V Lape]

 

Thought I would post this JP Beck to show one example of his lock placement.  I note he did exactly as Don Getz said and brought the wood straight down at the back of the barrel.

[Don Getz]

Jerry......this is just one of many examples Allen Martin pointed out, and he is a pretty good student of the longrifle.  Of
course, you can build them any way you want, I always found it easier to clean a gun the had a nice flat, shiny breech
plug, no recesses.   If you are one that "flushes" your barrel with water, then it doesn't matter what you do down there..............Don

[Acer Saccharum]

Did Beck use a Large Siler on that gun?

I much prefer Beck's treatment rather than leaving a little extension of wood that meets the back of the fence. It's hard to keep from breaking it off during building. It will probably be broken at some point in the life of the rifle, pulling the lock in and out for cleaning..

[Dr. Tim-Boone]

Did Beck use a Large Siler on that gun?

 Nah....  its one of Stan Hollenbaugh's locks.  JP went for the custom lock.................   He surely wanted itto look like the real thing