Finished my CO elk getter, a homemade underhammer percussion .50 cal (more pics added)

Wapiti1

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This project started in January when I decided which CO elk tag to apply for and it happened to be a muzzy season tag. I had the points and creep wasn't an issue, so I started to plan the build. I have several muzzleloaders, and initially thought that I would use a .54 Cal Lyman Trade Rifle. It's a great shooter, but I've shot a lot of game with it. Time for something different.

My criteria were to go with a traditional percussion rifle in .50 or .54 cal. A twist on that was that it needed to shoot any bullet I chose, and I wanted good ignition with any powder; black, or all substitutes. That last bit can be problematic with anything that isn't direct ignition to the powder charge like an inline. The 90 degree bend in a sidelock causes issues with ignition.

That left me, at least in my mind, with two designs to choose from. A mule ear or side slapper lock or an underhammer lock. The mule ear locks are good, but after looking at it, they seem prone to snagging on random vegetation and clothing when in the half cock position. The hammer sticks out a ways and they need a shroud of leather, IMO. They also provide no weather protection to the cap without that lock cover.

Underhammer locks are tucked up neatly underneath and make a simple and sleek arrangement. The cap is protected, and the hammer is as well. The underhammer has several iterations dating well back into the 1800's.

In both of these designs the blast from the cap has a direct line to the powder charge with no 90 degree turn to make like on a standard sidelock.

After making that decision, I gathered materials and a barrel. The things on this that I didn't make from scratch are the barrel, ramrod, and sights. I made the rest of the parts, including the screws, in my shop and heat treated them as required. I blended a few designs to make this rifle and anyone that is familiar with the old Numrich Hopkins and Allen will see a resemblance, but it has more in common with the Billinghurst lock. The trigger guard acts as the mainspring for the hammer.

So, the specs are a repurposed TC Omega barrel. It was cheap, in good shape, and has the right twist for conicals. Musket cap ignition for the extra horsepower. Tru-Glo ghost ring sights. Quilted maple stock. German silver sandcast buttplate. Lock and all other parts made of appropriate steel and rust blued.

Honestly, it's a simple design and anyone with a drill press, torch and some files could make it. Fun project that should prove to be a fun hunting arms for many years to come.

No idea how it shoots yet. I'll update the post when I get it out.

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Jeremy
 
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blazingangel09

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Awesome build and a gorgeous rifle. I would love to see a breakdown of your build process.
 

FrontierGander

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powder flows into a bolster or into a drum, so the nipple flash is going directly into powder, not empty space.
 
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Wapiti1

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powder flows into a bolster or into a drum, so the nipple flash is going directly into powder, not empty space.
I disagree that you can get that to happen reliably enough to ignite modern substitute powders. Pyrodex, sure, Triple 7? Not likely. To me, the requirement of using any sub changes the game.

Powder has a funny way of bridging and not flowing properly. You have no way to guaranty the powder made it into the drum. Tap it, shake it, whatever. It might, or might not. #11 caps are weak, IMO. Musket caps help, but I still don't think they get you there.

90 degree turns reduce flame strength regardless of what the flame ends up igniting. I liken it to loss in hydraulic, air or water pipe systems. Bends create loss.

Am I right? I have no idea. I'm just applying my experience with muzzleloaders and other similar systems.

Jeremy
 

Fordguy

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I used to take out the screw that allows you to clean the channel that the flame takes, tap a little powder into the channel, and replace the screw. I don't remember ever having a misfire or a hangfire after doing that. Flame from the no 11 percussion cap makes contact with powder in the channel which is either in contact with powder in the bottom of the barrel or makes enough flame for a reliable ignition otherwise.
 
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Wapiti1

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I used to take out the screw that allows you to clean the channel that the flame takes, tap a little powder into the channel, and replace the screw. I don't remember ever having a misfire or a hangfire after doing that. Flame from the no 11 percussion cap makes contact with powder in the channel which is either in contact with powder in the bottom of the barrel or makes enough flame for a reliable ignition otherwise.
You did that while hunting? Were you using T7 or BH209?

I've never had to do anything extra to get any of my sidelocks to be reliable with pyrodex or black.

This rifle will not see Pyrodex or black powder. I prefer T7 and BH209. Hence the choice of lock. If needed the design is easy to modify for a 209 primer ignition.

Jeremy
 

kpk

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Very nice work! I'd like to see more details and closer up pics as well.
 

Fordguy

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You did that while hunting? Were you using T7 or BH209?

I've never had to do anything extra to get any of my sidelocks to be reliable with pyrodex or black.

This rifle will not see Pyrodex or black powder. I prefer T7 and BH209. Hence the choice of lock. If needed the design is easy to modify for a 209 primer ignition.

Jeremy
I did do it while hunting if I needed a second shot. Everywhere I've hunted with a muzzleloader the gun isn't considered loaded unless you have a percussion cap on the nipple or primer in place- so usually I would prep the gun this way before I left the house. Patched round ball over 85 grains of pyrodex or triple 7 with powder in the channel. Wish I had never used the pyrodex. Seems like no matter how many times I scrubbed and oiled a barrel it would rust. Ive never tried bh209 in a sidelock.
 

FrontierGander

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Even when using t7 and pyrodex, flow wasn't an issue. Some designs like lyman have a tiny hole for the powder to flow and that can be an issue, but its a design flaw, not a powder issue. Heck, finding burrs left behind from machining is actually a big issue on sidelocks these days.

Nipples also perform differently from one brand to the next. Todays nipples use a much smaller flash hole than the nipples of long ago.

Patent breech,

CVA/Traditions style drum.


I shoot Gearhart - Owen 2fg and 3fg these days, but back in the day, Pyrodex RS, American Pioneer, Black MZ, were all I shot due to me not having black powder on hand easily. Thats changed! But if you are shooting a sidelock, black powder * real stuff * is the best way to go as thats what these rifles were designed to shoot. Switching to a Knight Redhot or a Spitfire nipple increases performance/reliablity, greatly when using black powder subs.

Just to give you an idea of the powder granulation I can easily get to flow through my traditions drums.


That's a sharp looking under hammer you made! I cringed when I saw that you used a TC barrel for shooting conicals, so I look forward to seeing your first shooting report.
 

Fordguy

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I would double like this if I could. My favorite old cva 50 has a burr in the channel that I've never been able to remove completely. Always been too worried about damaging the threads. Its a very accurate rifle with a round ball as long as you keep the powder below 90 grains, and a ton of fun to shoot. The OP has built a beautiful underlock. Wish my sidelocks had wood like that.
 
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Wapiti1

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Even when using t7 and pyrodex, flow wasn't an issue. Some designs like lyman have a tiny hole for the powder to flow and that can be an issue, but its a design flaw, not a powder issue. Heck, finding burrs left behind from machining is actually a big issue on sidelocks these days.

Nipples also perform differently from one brand to the next. Todays nipples use a much smaller flash hole than the nipples of long ago.

Patent breech,

CVA/Traditions style drum.


I shoot Gearhart - Owen 2fg and 3fg these days, but back in the day, Pyrodex RS, American Pioneer, Black MZ, were all I shot due to me not having black powder on hand easily. Thats changed! But if you are shooting a sidelock, black powder * real stuff * is the best way to go as thats what these rifles were designed to shoot. Switching to a Knight Redhot or a Spitfire nipple increases performance/reliablity, greatly when using black powder subs.

Just to give you an idea of the powder granulation I can easily get to flow through my traditions drums.


That's a sharp looking under hammer you made! I cringed when I saw that you used a TC barrel for shooting conicals, so I look forward to seeing your first shooting report.
Thank you for the photos to go with your commentary. The issues that I have seen were almost all with import sidelocks and those also all had tiny flame channels. The solution was a small priming charge of triple or even 4 F followed by the main charge of 2 F or pyrodex. The custom sidelocks that I've shot all used a drum and those were better, but I never shot any with T7 or BH.

The TC QLA muzzle is gone on the barrel I used. I cut it off and re-crowned it as one of my first acts. The twist is right, so it should shoot well with a properly sized bullet.

Jeremy
 
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Wapiti1

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I did do it while hunting if I needed a second shot. Everywhere I've hunted with a muzzleloader the gun isn't considered loaded unless you have a percussion cap on the nipple or primer in place- so usually I would prep the gun this way before I left the house. Patched round ball over 85 grains of pyrodex or triple 7 with powder in the channel. Wish I had never used the pyrodex. Seems like no matter how many times I scrubbed and oiled a barrel it would rust. Ive never tried bh209 in a sidelock.
That's why I don't use Pyrodex any more. I'd hot water and soap clean it, grease it and a week later it would have grown red fur and need a hair cut. I never had as much trouble with good black powder, but pyrodex always seemed to do it.

Interesting that you would go through that in the field. I'm pretty sure that I'd drop the screw while in the stand never to be seen again.

Jeremy
 

FrontierGander

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i've shot a hundred + lbs of pyrodex in 20 years, probably more, but i'll be realistic :D

Could be something in the water that causes it for some folks.

Im on soft water ( well water ) and never had any issues. Hot soapy water, flush the bore a few times with clean hot water, dry patch, a shot of alcohol to flush out the breech, a alcohol soaked patch, dry it, follow up with favorite anti rust gun oil. Never had any issues like some have posted.
 
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I'm envisioning that plug going through your foot about .00005 seconds after ignition. lol
 
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Wapiti1

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i've shot a hundred + lbs of pyrodex in 20 years, probably more, but i'll be realistic :D

Could be something in the water that causes it for some folks.

Im on soft water ( well water ) and never had any issues. Hot soapy water, flush the bore a few times with clean hot water, dry patch, a shot of alcohol to flush out the breech, a alcohol soaked patch, dry it, follow up with favorite anti rust gun oil. Never had any issues like some have posted.
It's odd for sure. I don't have the same issue with black. Just the pyrodex. That said, I only shoot pyrodex in my sidelocks and just know I'll have to clean it the day I shoot it and a couple of days later. Black is too hard to get here, so I haven't shot it in a long time.

Jeremy
 
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Wapiti1

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Here are some more photos of the rifle to show some details.

The copper is a small blast shield to keep the forearm from turning black over time. I'll make a cup at some point out of brass or stainless.
IMG_0567.jpg
The barrel has the original breech plug thread and I made a plug from 17-4 PH stainless. It extends 3/8" from the barrel breech and threads into the breech block. That is locked with a screw on top that also attaches the top tang.

The breech plug is counter bored like in Frontiergander's pictures and the fire channel ends in that counter bore. The drum threads through the barrel and breech plug with a 5/16" thread. The drum is also made from 17-4 PH stainless.

The mainspring is 1075 steel at 0.055" thickness and 0.75" width. It was formed and then heat treated in my shop. The trigger and hammer are made from 4150 plate. Cut out, milled, and finished with files to get them shaped. They are very close to the old Numrich H&A in shape. Once finished they were also heat treated.

The breech block and lock plates are 3/8" and 3/16" mild steel welded together. Pins and the screws that I made are drill rod.

The stock is big leaf maple. I cut it to match the drop of a Hawken style sidelock that I have that fits me well. I added 1/4" cast off to the stock as well to fit me better. The forearm uses the original hanger the Omega had and I just made a bushing and screw for the forearm. The finish is a thinned brown stain with sanded in spar urethane. It gave the maple a nice tone and it really pops in the sun.

Like I said, it is simple and could be made with just basic tools and time. I thought it turned out well.

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Top tang inlet.
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Bottom tang and lock inlet
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Top tang, needs some filler screws for the TC scope base holes.
IMG_0569.jpg
Bottom of stock.
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IMG_0571.jpg

Jeremy
 

Fordguy

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That's why I don't use Pyrodex any more. I'd hot water and soap clean it, grease it and a week later it would have grown red fur and need a hair cut. I never had as much trouble with good black powder, but pyrodex always seemed to do it.

Interesting that you would go through that in the field. I'm pretty sure that I'd drop the screw while in the stand never to be seen again.

Jeremy
How often do you get a second shot with black powder? I can only think of a handful of times in the past few decades where I've had the opportunity to take a second shot.
 
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