02 December 2012

Scrap Bin Underhammer

Through the years of writing this blog I have always tried to encourage you readers to design and build your own underhammer arms. While many of you may feel that you just don’t have the skill or machinery or ideas to build, some of you have risen to the challenge and have made some rather interesting underhammers which you have been so kind to share with me. Some of them were rather crude and not well thought out before starting the work, while others were better examples of careful planning before starting the building process.

I would like to share with you some work from one of our readers, Robert Bradley. Unlike some builders who start with a ready made underhammer action, Robert decided to build an action of his own design. He’s a machinist who enjoys tinkering with guns and states that it was pictures of underhammer guns in books at the library that inspired him to try his hand at building one of his own.

The Bradley Boot Pistol

 Although he is a machinist, Robert does not have access to much machine shop equipment. So, his design had to be simple enough for him to build without the advantage of the precision machinery that many people believe is necessary in order to fabricate an underhammer. He did most of the work with hand tools.

Top and side plates have been removed to reveal the heart of the action.
Robert claims that the design just sort of evolved as he started putting pieces of scrap material together. In fact, the ¼-inch flat bar that forms the one side of the "receiver" and the hammer, along with the sheet metal side panels, he retrieved from the scrap bin at work. 

Close-up of the hammer and nipple.

While Robert did contour his barrel, one would not have to do so if you didn’t have the machinery available. For that matter, you could take your seamless tube to a machine shop and have it turned to your favored contour if you really wanted a tapered barrel.

While studying the photos of Roberts boot pistol, you will appreciate his design more in understanding that his trigger is not of the typical form which pivots on a pin. Robert’s trigger actually slides fore and aft on a track. The front edge of the trigger body, or the “sear” as we might call it, slips into a slot in the hammer to captivate it in the cocked position. It’s a very simple and effective design which requires less precise angles than a typical hammer/trigger arrangement.

Bottom view reveals the trigger and its pusher spring to the rear of it.

The top-strap also serves as the rear sight.
Now that he’s proven the design with this prototype, I’m sure he will now refine it – like replacing the round-head screws with countersunk flat-head screws which will provide cleaner lines and sleeker appearance.He mentioned, too, that he wants to fit a stronger hammer spring. One thing I would strongly recommend is the addition of a flash guard over the nipple as this design is likely to spit cap fragments everywhere - especially into the trigger finger and his pals.

What’s up next on Robert’s design board? He mentions, “I work at a shop that stamps brass and other metals. I also got some 5/8" round stock today and think I'm going to make a pair of .36 caliber derringers out of it. I want something really compact, so, I'm probably going to go with a ring trigger and spring underhammer to keep them small.”
So, take a look at Robert’s boot pistol and see if it doesn’t spark an idea for you, too.

Thanks, again, Robert, for sharing your scrap bin boot pistol with us and good luck with the derringers. We'd like the see them when you're finished.


All photos copyright by Robert C. Bradley


Anonymous said...

Nice pistol and post.

Mr. Renner, could you talk more about seamless tubing and how to use it as a barrel as opposed to a "purpose built" barrel -- types, specs, sources?

Unknown said...

I would really like to see how the barrel is mounted to the frame.

Unknown said...

I would really like to see how the barrel is mounted. Thank You.

Anonymous said...

You might check out that topic on some of the muzzleloading forums.

Robert Bradley said...

As I recall, the barrel was welded to the plate that makes the front of the frame. I'm also looking into using DOM tubing for barrels, but am not sure about proper wall thickness.

Rock Island Auction Company said...

Very neat project! Love the simplicty. Keep up the good work!

kyle said...

I was challenged by this article to build a scrap bin underhammer with items I had in my shop. The result is a functional .32 cal smoothbore.

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About Me

Roger Renner

Hi. I've been a student, admirer, and designer/builder of underhammer guns for over 30 years. In that span I've built over 200 semi-custom underhammers exploring the possibilities from the ordinary to the exotic. In 1996 I founded Pacific Rifle Company to explore the market's interest in a high-quality underhammer rifle. Thankfully, that interest was, and still is, there. I sold PRC in 2006 but continue to craft high-end underhammers as I am truly afflicted with underhammeritis - which can be contagious!