Locating position of drum on barrel

[MI MAN]

While looking over the plans for a percussion rifle I am building, I noticed some differences in where a drum is installed on a barrel. The plan drawing for my rifle shows the drum threads just in front of the breech plug. However the instructions for the jig used to locate the nipple on the drum shows the center line of the drum threads lined up with the face of the breech plug. Does anyone have any experience locating and drilling out the breech plug hole. Not sure what the proper procedure is? Thanks

 

[Larry (Omaha)]

While looking over the plans for a percussion rifle I am building, I noticed some differences in where a drum is installed on a barrel. The plan drawing for my rifle shows the drum threads just in front of the breech plug. However the instructions for the jig used to locate the nipple on the drum shows the center line of the drum threads lined up with the face of the breech plug. Does anyone have any experience locating and drilling out the breech plug hole. Not sure what the proper procedure is? Thanks

There are guys on here that will support one or the other of the two methods you have described. I have always heard that the ideal ignition is to the rear of the powder charge. I personally don't think a 1/4" makes that much difference on ignition/performance. If you go by the plan it will be an easier to do method, because you are not trying to encroach into two different thread space/areas. If you go the jig route, and ever have to pull the breech plug, the drum will have to go first, although not a biggy. The breech plug threads will need some work once the drum threads penetrate into them. With the ignition hole closer to the breech plug, when you swab, it is more likely to plugged.
I would go with the plan. What I told you is my opinion, but it is based on you not having the lock already installed. If the lock is installed, the arc of the hammer is going to dictate where the drum goes.
Flintlocklar

 

[Ames]

the arc of the hammer is going to dictate where the drum goes.

That's the part you have to get right! You can always fix it if you hit the plug threads, but if you mess up the angle of the hammer to the nipple you will be buying a new drum. $5, but a big pain while you wait for the UPS truck.

 

[Zonie]

While looking over the plans for a percussion rifle I am building, I noticed some differences in where a drum is installed on a barrel. The plan drawing for my rifle shows the drum threads just in front of the breech plug. However the instructions for the jig used to locate the nipple on the drum shows the center line of the drum threads lined up with the face of the breech plug. Does anyone have any experience locating and drilling out the breech plug hole. Not sure what the proper procedure is? Thanks

Your description confuses me.

In one area you are talking about the "drum threads just in front of the breech plug". I agree with this location. The center of the drum threads should be just far enough ahead of the breech plug face to allow about 1/32" of clearance. If the breech plug has 5/16" diameter threads on it, the radius of that would be 5/32". 5/32" plus 1/32 clearance equals 6/32 = 3/16" so the center of the 5/16" hole should be 3/16" in front of the breech plug face.

Then, you start talking about the nipple on the drum location which is a totally different kettle of fish. I agree with the idea that the center of the nipple should line up with the center of the drum. Most jigs for drilling the nipple hole will locate the threaded hole there.

Now, we come to the lock and its hammer's location relative to the center of the drum.
On all of the percussion locks that are made to be used with a round drum that I've used to build a rifle, they have a circular relief cast or machined into them. The purpose of this relief is to locate the lock, relative to the drum. If a drum, the same size as the relief is placed in that lock relief, the hammer will automatically be lined up with the center of the drum (if the lock maker did his job right).

What all of this boils down to is, if the lock is already located in the stock and the drum isn't going to be located in the locks drum relief, the barrel will need to be moved forward or aft until the features line up.
If the barrel is located in the stock but the lock is not, the lock must be moved forward or aft until the drum in the barrel line up with the locks relief.

As for the location of the nipple goes, you won't know where to locate it until you have the barrel and lock in the right position and assembled into the stock. Then, you can mark the in and out location and the angular position the nipple needs to be located at to line up with the hammer.

By the way, this whole thread should not be in the Percussion Rifle forum. It is a gun building question so I'm moving it to the Gun Builder's Bench forum.

 

[MI MAN]

Sorry for the confusion. My question was only for help on where to install the drum in relation to the breech plug. My kit plan shows the drum hole being drilled such that the left side of the drum hole (right hand lock) is just barely in front of the breech plug threads. One the other, the directions for the jig I bought to locate the nipple on the drum talk about installing the drum to the barrel; why I do not know. This set of directions show the drum hole going into the threads of the breech plug. The plan that came with the gun kit seems easier to. If i can help it and get just as good results I do not want to interfere with the breech plug threads. I have a choice because the barrel and tang have not been inlet to the stock yet. With the gun plan method it appears the job is done after the drum is threaded into the barrel; no re-work of the breech plug threads or anything else inside the barrel.

 

[Larry (Omaha)]

no re-work of the breech plug threads or anything else inside the barrel.

You want to utilize maximum threads of the drum, but do not want any protruding into the bore. The barrel wall thickness can be calculated for length of threads, but I personally like to view the result by having the breech plug removed.
Flintlocklar

 

[Pete G]

Do not drill into the breech plug. Place the drum just forward of the plug.

 

[M&P]

Do not drill into the breech plug. Place the drum just forward of the plug.

X2 I would follow the plan of your rifle.

 

[MI MAN]

Thanks for all the help.