Want to build underhammer. Need help.

[JNG3]

I've thought about this for a few years off and on. I want to build an underhammer muzzleloader this winter. Unfortunately there is little to no information on the internet in regards to these rifles. I like the H and A style and Pecatonica River sells both a kit of sorts and just the frame. That's probably what I will be buying. I have a slew of questions. Anyone here knowledgable on this subject?

[1Hawkeye]

Try deer creek products. I think they still have the H&A kits and actions.

[rfd]

http://www.longrifles-pr.com/images/UnderhammerLockw550.jpg

http://www.longrifles-pr.com/actions.shtml (http://www.longrifles-pr.com/actions.shtml)

[Boz330]

http://www.longrifles-pr.com/images/UnderhammerLockw550.jpg

http://www.longrifles-pr.com/actions.shtml (http://www.longrifles-pr.com/actions.shtml)


That looks exactly like the Deer Creek action that I just finished. Very simple and reliable.

Bob

[oldracer]

The folks at Pecatonica River are great. I bought the components this past winter and used the "Allen" action since it can be adjusted to give a lighter trigger pull where the H&A can not. You can have your choice of barrels and also type of wood and I used a Green Mtn. 45 caliber 1 in 18 twist for shooting 540 grain grease groove bullets. I got the fanciest piece of maple they could scare up and I also asked them the cut the dove tail for the front sight. There was very little wood work to be done but lots and lots of sanding!!!

I forgot to add that I asked them to fasten the barrel to the Allen action as I don't have a way to do that and line up the front sight dove tail. Smoothing the barrel flats and polishing the sides of the action were easy, just took some time and I blued them with Oxpho Blue, about 4 coats so the finish is nice and dark.

After shooting it several dozen times I broke down and installed a recoil pad since the gun was very light and with 100 grains of FFG my shoulder cried uncle! Recoil is much nicer now!

[oldracer]

Here is how it came out. Sure like them folks!!!

[MFGordon]

You may want to take a look at the Billinghurst style of underhammer.

https://www.muzzleloaderbuilderssupply.com/mbs3cart/agora.cgi?&product=Underhammer

[JNG3]

First question, how does one go about installing the breech plug in the barrel for the H&A type? It obviously screws into the barrel. What else needs done? How tight? I can't believe one simply just screws it in and that's all there is to it. For the record I'm referring to the H&A type shown in this thread and a Colerain barrel since GM barrels are rarer then hens teeth.

[oldracer]

I have no idea of how it screws in, that is why I asked the folks at Pecatonica to do it!!!

[JNG3]

So no one is willing to share details? Look I can cut dovetails for sights. I can solder thimbles. I can draw file. I can brown and rust blue. Etc, etc. I've never installed a breech plug and would like to know how to do it correctly. It can't be that much of a 'state secret'.

[oldracer]

As I said, I have no idea so I asked the folks at Pecatonica to attach the barrel to the action block so the top flat would be sitting level. They did. I imagine if you ask, they can tell you the tightening torque and then it is a matter of putting the barrel on. measure the top flat to see how it lines up with the top of the action. Measure, trim the end of the barrel, repeat. I asked the most noted gun smith in our area and he said it is try, measure, retry, ETC, ETC and then he said since they di it for free........have them do it!. If you want to do all the dove tails as I have done that is pretty easy once the barrel fitting is done. For $20 it is almost worth it to have them do the necessary dove tails. As I said give them a call as they will gladly let you know what is what.

In thinking about it, all the rifles, except one I had the company install the breech plug. The one I did had been disassembled so I knew it would fit okay. After tightening the plug hand tight, there was about 20 degrees of turning to make the flats line up. Whew that was hard!

[KCSO]

If you can fid it Buckskin report had a step by step on this in the 70's. I use a dial caliper to measure the length of the plug and the depth of the barrel threads. Then mark your top flat and start with the breech threads a little long. Screw it in and see how far off you are and then carefully file off just a little and try again. It won't take too long and you will be up to snff. I use inlet blackon the face of the breech plug and the back of the barrel to verify proper contact. Ideally the flats will line up and the inside of the barrel wil show full contact and the back of the barrel will be 80% or better with no gap showing on the top flat.

[bob208]

I made a round breach for mine. after fitting it and installing it I used the barrel flats as a guide to mill it to match the barrel. on the h and a the barrel fits into the action and is held with a tapered pin. on latter actions it is held with a screw. it is harder to describe then to do.

I wish people would put a location in their profile. then we could tell if you were across the field or across the country.

[kcajeel]

Here is how it came out. Sure like them folks!!!

Wow, thats quite a sight you have there. You can shoot your balls way down range with that.

[John Taylor]

The H&A underhammer uses a 5/8" breach plug that screws in the barrel and has the end butted up on the inside to seal it. The old ones used a taper pin to hold it to the action, later ones use three set screws. Cutting a 1/8" groove on the end and using a large screw driver or other device to tighten it up will work. I usually tighten and loosen several times to make sure it has a good seat. The fit of the breach plug to the action should be very close. This is one area you don't want a loose fit. On some of the actions I have made I thread the barrel and action so the action can be tightened to the barrel and not have any movement. This works good for accuracy but the rifle can not be taken down for cleaning easy. I have been building underhammers for about 40 years. While I do have a couple H&A stile actions I usually make my own using solid steel or brass bar, drilling it the bending it in the press.

[kcajeel]

John,

I have a H&A underhammer that came with a 3/4" Weaver scope on it. I can't shoot it like this in my club matches. Can you recommend a receiver sight that would fit onto it?

Thanks,
Jack Lee

[JNG3]

Thanks for the information on the breech plug. It cleared up a question or two for me. One last question. This concerns the nipple. The nipple is 1/4-28. I have a tap of this size and pitch. I also know this requires a drill bit of .2138" or #3. Do I drill and tap this hole all the way through the wall of the barrel? This would put all of the pressure of the burning powder on the nipple. I know this may seem like a dumb question but I am used to nipples being threaded into a drum or a patent breech and not the barrel directly.

[jwiant]

I would recommend a small book called "The Undergammer Rifle" by Jeff Baron. It has many different styles that are simple to build from scratch. It also covers some of the basic problems encountered with building one. I have built two of the locks; the cooper pistol and the wood lock rifle. I have to still finish the wood lock but I have shot it. I breached this one with a grade 8 bolt and then cut it off. Then tapped a hole in the receiver and used brass shim stock between them to get the flats to line up.

[Boz330]

John,

I have a H&A underhammer that came with a 3/4" Weaver scope on it. I can't shoot it like this in my club matches. Can you recommend a receiver sight that would fit onto it?

Thanks,
Jack Lee

This is what I used. It is from Muzzle Loader Builders supply. It is held on with 2 6-48 screws.

Bob

[kcajeel]

Thanks for the reply Bob. Thats an option but I'd really rather have something in more of a target type of sight. Something that I can change the elevation and windage with. My Thompson Hawkens wear Lyman 57 SML's . They work out really well when I change yardage at a match. I can dial in the necessary up elevation instead of increasing my load.

Thanks