So, I have built a few small falling block rifle actions over the last few years-mostly they were just not up to the level of finish for me to be happy with. They have since have had the barrels pulled and the receivers cut through the ring-not because I felt they were unsafe, but I just wasn't happy with them. Didn't want someone to come across them later, and potentially make them unsafe by trying to improve/rebarrel/overload them.

Anyway, I am going to build one to test my new cartridges with, it won't need a high level of finish, as long as it all fits and functions that's all that matters for a cartridge test gun.

But, while I'm working on this...what about a double? I've seen it done a few times, but always 30K$ plus, huge cartridges, and utterly brilliant fit and finish.

So, as I sit here drawing up the simple, exposed-hammer, toggle-locked design I've used in the past, with no frills, no features, no nuthin', I can't help but be distracted by the allure of an internal-hammer, or striker-fired design. There's a lot of extra work involved, like figuring out how to cock the action, trigger selection, the safety, all that jazz.

Does anyone have experience with internal hammer falling block actions, and thoughts on how they could, and should, work?

You might pick up a copy of "Single Shot Rifles and Actions" by Frank De Haas. that is if you don't already have one. Lots of good information.

Get the book, British Single Shot Rifles; the Farquarson or Alex Henry (can't find mine at the moment) one and they have a lot of the original patent drawings in them for several ideas on what you want to do.

Bailey Bradshaw did a falling block double (very high end). But I think he posted here as he built. Might do a search and it might give you some ideas. And I second the Frank De Haas single shot books idea. He wrote 4 or 5. They have detailed diagrams of the action pieces. Then he wrote a book on building a simple one. All will likely trigger good ideas. Finally, Bill Holmes wrote several books on building weapons. Some were focused on specific model builds, but he had a more general book called "Home Workshop Prototype Firearms" that presented lots of action types (including a falling block single shot) and various trigger mechanisms. Hope this helps.

Steve

http://www.africanxmag.com/the...ling_block_rifle.htm

You must be one of those who like abuse!

Building a double isn't twice has hard as a single-just about 5/3rds the work.

It's still one stock, still one receiver, so not *everything* is doubled, LOL!

And since I'm already building a single at the same time, I just build six of everything and I should get at least three pieces to come out right. Now, to go pick out a tree....coming up in march they'll be cutting and clearing an old apple grove, some of those trees are 18" across in the trunk. If I cut in march, then in two years when the actions are nice and slick and I'm happy with their performance, I'll have some wood to stock 'em with.

I'm looking at how much meat needs to be left in the barrel shanks, as all the doubles I can find are fairly thin-but of course, I can't go measure one to find out.

But, since this may turn out decent, I'd like to set up the design to handle a .44 magnum case, without having to change the barrel shank diameter. Looking at some of the revolvers chambered in both .357 and .44, I find that they have the same barrel shank between the two-S&W's model 29 at 0.670-36 and Ruger's Redhawk at 3/4-20. If I go with the .670-36 thread, I would still have room to leave a barrel shoulder, and the barrels just touch at the receiver.

If I can use 0.670-36 diameter shanks, then I can have the receiver wind up right at 2" wide-or I can go with a 2.25" wide receiver and use the 3/4-20 threaded shank. Going with the 3/4" shank seems like the best way to go but then I'll have quite the gap to fill at the end of the 20" barrels. Using the narrower receiver, the barrels I have will leave a 0.200" wide gap at the muzzles, this seems right for the regulating wedge?

My main concern is having enough material between the two barrels in the barrel shank area of the receiver. The material for the receiver will either be AISI 4142 or AISI 8620, I already have a big enough chunk of 4142 for the single-barrel model. The receiver walls will be a minimum of 0.125" thick, at the 55,800PSI yield strength of annealed 8620 (the lowest of the two steels) the thrust on the block would have to be 20,924PSI to plastically deform (stretch) the receiver. So, I don't think it will have a problem being strong enough!

I’ve regulated close to 100 doubles, done around 30 shotgun to rifle conversions, I’m building two break action double rifles from scratch now with more to come, and I apprenticed under Bailey Bradshaw building double barrel and single barrel falling blocks. I’ve still got a lot to learn!

Typically you want around .200”-.250” minimum wall thickness around the chamber tapering down to .100” wall thickness at the mid barrel point, then carry .100” wall thickness to the muzzle. For a .44mag is go .200” around the chamber.

You’re in for a surprise on difficulty of the project. Timing is extremely critical with them and the inherent pitfalls present with traditional falling block designs are magnified. Not to say you can’t do it, but the margin for error is slim. Single shots are a breeze in comparison.

Just like eatin' an elephant. It's not the first falling block I've built. In the past, I didn't leave enough stock on the parts to finish them without making the fits sloppy. Mostly, it's because I was using cold rolled material, and I also did not own any machine tools other than files and a drill press.

So yeah, the last ones I built, while functioning perfectly, looked like they were built by Kyber Pass apprentices. And that's not too far from what they were. I have spent much more time working with finishing processes and learning to leave more material since.

It may be a while yet, because I'm finishing up a CETME-L build in a caliber that has never been fired in a fluted chamber roller-lock. I have to finish up the forward assist and rear sight block, then the welded assembly starts. Probably another 40 hours of work to call that rifle finished.

Just for reference; Marlins have thread diameters of .777, so a 45-70 has chamber wall thickness of .140, and .44 Mag;.160. That is under threads too.
4140 steel is strong.

quote:

Originally posted by Aaron Little:
I’m building two break action double rifles from scratch now with more to come,

Hey, you can't just post that up without showing us some pics of the work in progress!

I come here to see guy's work, setups and learn.
Thanks!

I’ll post build threads once completed. These two are going to be round action trigger plate guns much like Dickson or McKay Brown, although they will have snap action underlevers that will cock the hammers and draw the sliding lock like seen on Woodward “Automatic” doubles. So a combination of sorts. Due to the solid action bodies I can make them smaller than a boxlock or sidelock whilst keeping strength and mass.

The action bar only has the cavities for the lumps and the sliding lock slot machined in it, and the standing breach will only have the firing pin holes in it(no top lever). I’d wager to say they will be the strongest break action double actions in existence...feathers ruffled. First two were commissioned by an individual and will be a .700ne and 4 bore.

Martin Hagn showed me a very nice little falling block double he had made in 7x57. This was roughly twenty years ago. I don't know how many he has built. I do know he was working on design variations. Regards, Bill

Worked on the breechblock for this design a bit today, firing pin pockets mostly. I'm planning on using an inertial firing pin, because I just don't have the skill or tooling to implement a mechanical retractor.

Something I am marking down as a design goal is zero open holes/gaps in the loading area-I do not want crap or dirt getting down into the action from the open breech. So far, that has been simple-we'll see if it stays that way.

Good luck with your build I am sure by the time you are down you well have learned a great deal.