Falling Block with clam shell or sandwich receiver

[Dmitri Popov]

I'm going to be starting a falling block build soon, and I'm trying to decide on some design choices.

I'm trying to decide if i want to go with a solid receiver with a round breech block (similar to Darcy), or a square block but of a "sandwich" or clamshell receiver (kinda like a chicopee).

I've got some stuff drawn up, and will be incorporating several different ideas from other guns into this. I do not intend this to be a copy of any particular rifle, but rather just something fun for me to shoot. I will most likely be chambering for 45 colt.

Given the choice between the two styles I've listed, what would the group here do? I welcome all feedback and suggestions. Also any pictures from wherever would be greatly appreciated!!!

Also please note, I'm writing this at 3 am so I may have left out details important to this discussion, so please forgive me and just ask!!!

[uscra112]

Depends a lot on what machine tools you have. Although I knew a guy in England (sadly now deceased) who built an entire Sharps-Borchardt on a little benchtop hobby mill, it took him a loooong time.

Sandwich gets you out of having to broach the breechblock mortise. Ought to be sturdy enough for .45 Colt. Not for the high pressure rifle cartridges.

I've seen the round breechblock designs that DeHaas published, which gets you out of having to broach, but IMHO they are ugly as sin. (I have his book.)

That's my nickel's worth.

[Dmitri Popov]

Those were my thoughts as well. I load all my .45 to SAA spec so that I don’t accidentally put a hot load in my revolver, not to mention I only plink with my 45’s anyway. If I go round block, I will NOT be going with Frank’s rifle’s lines. Probably more like a high wall with round block.

And yeah, I don’t have the ability to broach or EDM from home (nor the desire to get setup to honestly) and I don’t want to have to outsource any of the work except maybe some TIG work.

I appreciate your input!

[country gent]

A couple guys were working on Sharps receivers together in the shop on lunches and weekends. They did the block cut outs with the wire edm. On the originals they were broached. For a one off home project drilled thru and carefull hand filing to remove the radiuses can be done.

[Dmitri Popov]

I’ve thought about that as well. Still considering building a die filer for jobs like that. I’m just not sure I want to get into that on this rifle since it’s going to be a plinking/fun gun. Not saying I’m not going to put effort into making it look nice, just not wanting to build an exact copy of an existing rifle, so I don’t think that level of effort is necessarily needed. The other issue I run into is availablity of materials. I don’t have any great sources locally for suitable steel. I think the laminated or clamshell receiver would help a lot on sourcing material.

[oldred]

Seriously that breech block mortise is not nearly as difficult as it might seem, I have used a couple of methods to do that and it was done in 4140 PH (pre-hardened) material. I first drill a hole in the center of where the mortise is to be located just a bit smaller and at the proper angle. The receiver is then set up with the mortise in a vertical position and milled square (actually rectangular) using a 1/4" carbide end mill long enough to reach all the way through, a 4" long mill is normally long enough. That leaves the corners with a .125 radius which on the first ones I did I filed down using some simple guide plates. The last couple I did using a broach I modified slightly and a block I made to guide the broach, either way is not nearly as much trouble as it might seem.

There may be several reasons someone might want to use a multi-piece (or layered?) receiver but personally I would not let that breech block mortise stand in the way of a one piece option if that's the only reason and the one piece is what is really wanted.


Just another note on doing that mortise, a buddy of mine started a HighWall but lost interest and never finished although he did do the mortise before stopping (he works 10 hr shifts all week and just didn't have time for the project). He did as I did on mine except that he used a small easily made HSS steel bit mounted in a drill press with the receiver clamped in a 2 axis drilling vise. He locked the spindle so it wouldn't turn and then simply used this rig as a sort of manual shaper removing a few thousandths of metal on each down-stroke until the corners were down to where he wanted them. I didn't watch him do this but he described how he did it and I saw the finished result which was quite good, it took only a bit of clean up filing and that thing was then ready to fit the block.

Actually there are several ways of doing this even without things like heavy mills, etc as I actually did my first one on a lathe because I didn't even have a good drill press at the time never mind a mill. The lathe and home made milling attachment worked quite well however and while a true mill is better of course it isn't an absolute necessity. The point being is if you want a HighWall style rifle, for instance, then don't let things like that mortise be the deal breaker, it really isn't all that hard to do.

[john.k]

Do All used to advertize that it was possible to cut out all kinds of complex shapes with a bandsaw......but the catch was that you had to be able to weld the tiny spiral saw blade......which they claimed was childs play....As far as manual slotting ,well someone else can do it,not me....I see no reason why a welded up receiver would not be satisfactory ,provided that the welds were sound.....not difficult with Mig........there is another point to consider,rolled plate has a rolling direction,and should not be used across the "grain".

[oldred]

Well I suppose a welded receiver would be fine for smaller cartridges and maybe something like 45 Colt with no more than midrange loads but welding does add a few variables, if a really strong alloy steel is wanted then something like 4140 can be welded but it's tricky to do and get it as strong as a solid part to start with, still it "could" be done.


I honestly think the difficulty of doing this is overblown, I have done it myself several times so I am not guessing about what's involved. If even a small mill is available then getting the mortise finished down to a 1/8" radius in the corners is no big deal at all nor does it take long to do, at that point there are several good ways to reduce the corner radius down to the .015 +/- (plus or minus quite a bit actually) that is normally used in something like the 1885 receiver.

I have over 40 years behind me as welder so I know too what is involved in doing that and when all is said and done there would be nearly as much, or even more, time and effort involved in welding two halves together and then still have to finish work the mortise after welding. Really fellas cutting that mortise is not all that big a deal!

[Dmitri Popov]

Oldred, thank you for your feedback. Although my post count isn’t high, I’ve been around a while, and I know you know what you’re talking about.

So you’ve got me thinking more and more about going solid receiver. The problem I run into is, is the square block really worth it for what I want out of this particular rifle. In your opinion, purely from a usage standpoint, not aesthetics, is there an advantage to a square block over a round one? In my head it seams, aside from ease of manufacture, a round block would be quite strong due to there not being the sharp corners. I know from the general theory of homebuilt cannons (I build miniature ones) sharp corners, such as at the bottom of bores, are seen as weak points. Though that theory has never sat totally right with me because of my experience with muzzleloaders and their use of square faced breech plugs.

I guess basically what I’m asking, is if I do it right, would I sacrifice strength by using a round block?

[john.k]

The back thrust against a breech block is at absolute max under 10 tons......and usually is very low,due to the strength of the case.......There are two historic round breech guns that come to my mind.....first would be the Krupp cannons,where a round block withstood massive force,and second would be Christian Sharps falling block pistols,an oddity....Appearance is the only reason for objection,and tradition.If you want a round block,go for it......its only a few bucks in steel,and if you dont like it,start again.

[oldred]

I guess basically what I’m asking, is if I do it right, would I sacrifice strength by using a round block?

No I would think not and in fact by using the round block you would be completely eliminating the stress risers formed by the corners which are the weakest points for a square block design. There would be a few other issues to address when using a round block such as need for the flat face for the breech and the need for a secure means of holding the block securely in position so that it does not tend to twist in the receiver bore. Of course these are easily taken care of minor problems, probably minor to the point of just being considerations rather than actual problems. For instance it would seem that just the lever attachment itself would be sufficient to prevent the block from turning in the bore enough to cause a problem as long as everything is a snug fit.

I would also suggest your design include an angle on that breech block bore of 5 or 6 deg from vertical otherwise loose headspacing will always be a problem and could easily develop into a serious problem if the block is straight at 90 deg to the breech. The reason for this is that with a simple 90 deg arrangement any clearance, even the necessary clearance required for movement, between the block and it's bore/mortise will automatically translate into headspacing looseness. By angling the block to the breech and then having a flat face milled in the block at 90 deg the block can wedge itself tightly against the breech without becoming stuck and will provide for a solid lock-up between the barrel breech/cartridge case head.

[dave roelle]

I have always wondered why falling blocks must have square corners

I have several Highwalls and Sharps and a small corner radius would increase strength and ease machining

Dave

[Moleman-]

Read through this thread on a 45-70 using a round block. http://castboolits.gunloads.com/show...y-Rifle-Action I got a block of 4140 prehardened to make one at some point hopefully after deer season.

[john.k]

The catch with hammer pivoting in the frame is that the action needs a fair bit of drop to get the hammer out of the way.This is the big sale point of the highwall,the hammer disappears for loading...I personally prefer a side hammer with a back action lock,rather than a fixed central hammer.....There is a clever design by Soper that uses a narrow block,with an inline type striker in front of the block,firing via a rocker in the block.

[oldred]

I have always wondered why falling blocks must have square corners

I have several Highwalls and Sharps and a small corner radius would increase strength and ease machining

Dave

They do have a small corner radius, the HighWall for instance calls for a .015 radius in the corners. A large radius is simply not required and the legendary strength of the HighWall design is testament to that! If a person were to broach that mortise with a normal sharp cornered broach that would likely reduce it's ultimate strength quite a bit but just a small radius such as the .015 if cut smoothly (a ragged cut would be worse than no radius!) should eliminate any problems as indeed past history seems to indicate it has. A bigger concern is failure to include a proper radius in the corners of the extractor relief cut into the chamber in the barrel.

This round block vs square block decision really should not be based on difficulty or time involved, fellas when we build a rifle we need to consider just why we are doing it. This is a hobby not a job and although time needs to be considered to a point it should not be the major concern, if it is then the project becomes a task instead! If building a rifle is just a means to an end, to save money, to obtain a type of rifle that may be hard to find, etc, then the task can be daunting and less than enjoyable with these things usually being apparent in the finished rifle. If we take our time to actually CRAFT a rifle rather than just build/assemble it then that too will be apparent in the finished version, this is supposed to be an enjoyable endeavor with each step (such as that mortise) being a part of it to be accomplished with the love of the work not just another hurdle that must be overcome so that we can continue.

When I built my HighWall rifles i didn't like the (to me anyway) cluttered appearance of the receiver sides due to the relatively large lower tang retainer screw heads or the ends of the sear pin showing on the outside of the receiver. It took a lot of head scratching and a great deal of extra time and effort to eliminate those things and end up with a cleaner appearance, all for really nothing more than it was just the way I wanted it. The point I am trying to make there is that what you really want is what matters more than time and effort, this is a hobby to be savored and enjoyed not a task to be endured simply to obtain a rifle, the finished product should incorporate all the things we want in that rifle and not be an assembly of compromises that saved time and effort.

Build what you want the way you want it, any time and effort saved for the sake of expediency was just a temporary convenience but the finished rifle is forever!

[John Taylor]

I think it would be great if someone built a Phoenix action. Most likely it could all be done with a mill, no broaching. The trigger guard/lower tang is almost identical to a Remington roller. Breach block swings out like a Snider but the hammer is inline with the bore. I have an original in 12 gauge that will someday be barreled up as a rifle. The Phoenix was made by Whitney after Remington sued them over the rolling block.

[Dmitri Popov]

No I would think not and in fact by using the round block you would be completely eliminating the stress risers formed by the corners which are the weakest points for a square block design. There would be a few other issues to address when using a round block such as need for the flat face for the breech and the need for a secure means of holding the block securely in position so that it does not tend to twist in the receiver bore. Of course these are easily taken care of minor problems, probably minor to the point of just being considerations rather than actual problems. For instance it would seem that just the lever attachment itself would be sufficient to prevent the block from turning in the bore enough to cause a problem as long as everything is a snug fit.

I would also suggest your design include an angle on that breech block bore of 5 or 6 deg from vertical otherwise loose headspacing will always be a problem and could easily develop into a serious problem if the block is straight at 90 deg to the breech. The reason for this is that with a simple 90 deg arrangement any clearance, even the necessary clearance required for movement, between the block and it's bore/mortise will automatically translate into headspacing looseness. By angling the block to the breech and then having a flat face milled in the block at 90 deg the block can wedge itself tightly against the breech without becoming stuck and will provide for a solid lock-up between the barrel breech/cartridge case head.

That's what i was thinking as far as strength. And yes, the lever will be the anti rotation device. Also a 5 deg slant will be incorporated.

Read through this thread on a 45-70 using a round block. http://castboolits.gunloads.com/show...y-Rifle-Action I got a block of 4140 prehardened to make one at some point hopefully after deer season.

I love this build. Already have a folder on my pc with every pic I could scrounge detailing his design. Would love to find more! Darcy is actually who inspired me to go round block.

The catch with hammer pivoting in the frame is that the action needs a fair bit of drop to get the hammer out of the way.This is the big sale point of the highwall,the hammer disappears for loading...I personally prefer a side hammer with a back action lock,rather than a fixed central hammer.....There is a clever design by Soper that uses a narrow block,with an inline type striker in front of the block,firing via a rocker in the block.

I am most likely going with an inline hammer, that when cocked, will be flush with the receiver. I think I'm going to incorporate a side lever for cocking similar to a Soper.

They do have a small corner radius, the HighWall for instance calls for a .015 radius in the corners. A large radius is simply not required and the legendary strength of the HighWall design is testament to that! If a person were to broach that mortise with a normal sharp cornered broach that would likely reduce it's ultimate strength quite a bit but just a small radius such as the .015 if cut smoothly (a ragged cut would be worse than no radius!) should eliminate any problems as indeed past history seems to indicate it has. A bigger concern is failure to include a proper radius in the corners of the extractor relief cut into the chamber in the barrel.

This round block vs square block decision really should not be based on difficulty or time involved, fellas when we build a rifle we need to consider just why we are doing it. This is a hobby not a job and although time needs to be considered to a point it should not be the major concern, if it is then the project becomes a task instead! If building a rifle is just a means to an end, to save money, to obtain a type of rifle that may be hard to find, etc, then the task can be daunting and less than enjoyable with these things usually being apparent in the finished rifle. If we take our time to actually CRAFT a rifle rather than just build/assemble it then that too will be apparent in the finished version, this is supposed to be an enjoyable endeavor with each step (such as that mortise) being a part of it to be accomplished with the love of the work not just another hurdle that must be overcome so that we can continue.

When I built my HighWall rifles i didn't like the (to me anyway) cluttered appearance of the receiver sides due to the relatively large lower tang retainer screw heads or the ends of the sear pin showing on the outside of the receiver. It took a lot of head scratching and a great deal of extra time and effort to eliminate those things and end up with a cleaner appearance, all for really nothing more than it was just the way I wanted it. The point I am trying to make there is that what you really want is what matters more than time and effort, this is a hobby to be savored and enjoyed not a task to be endured simply to obtain a rifle, the finished product should incorporate all the things we want in that rifle and not be an assembly of compromises that saved time and effort.

Build what you want the way you want it, any time and effort saved for the sake of expediency was just a temporary convenience but the finished rifle is forever!

I appreciate that comment and sentiment. The more I think about it though, the more I actually want to incorporate the round block. Beyond just the ease of manufacture, I think I can make it look good. At the very least it will be unique!

I think it would be great if someone built a Phoenix action. Most likely it could all be done with a mill, no broaching. The trigger guard/lower tang is almost identical to a Remington roller. Breach block swings out like a Snider but the hammer is inline with the bore. I have an original in 12 gauge that will someday be barreled up as a rifle. The Phoenix was made by Whitney after Remington sued them over the rolling block.

I'm a huge fan of the Phoenix! I have a file of pics of it too. I would love some actual drawings for it. Or at least measurements of an original action. Info like that is hard to come by though as far as I can tell.

[William Yanda]

I am not a machinist, (didn't stay in a motel last night either), trying to picture this. Is a middle road possible with a large square block, cut down, with a side bolted on a possibility?
respectfully,
Bill

[oldred]

The more I think about it though, the more I actually want to incorporate the round block. Beyond just the ease of manufacture, I think I can make it look good. At the very least it will be unique!

Several very good reasons to do so and I wasn't trying to sway your decision, in fact I think that round block (or cylindrical block) is an excellent choice but my point was to build what you want in your rifle and not let perceived difficulties be a game changer that might lead to something regrettable later.

Darcy is actually who inspired me to go round block

And a great inspiration that is! That one is truly unique despite the builder's modesty in claiming it is more of a collection of previously used ideas, he had every right to claim a new design there and one anyone should be proud of.

[oldred]

I am not a machinist, (didn't stay in a motel last night either), trying to picture this. Is a middle road possible with a large square block, cut down, with a side bolted on a possibility?
respectfully,
Bill

I could be wrong but IMHO bolting a receiver would not be a good idea, well maybe for something like a 22 RF might be Ok. As mentioned by someone else welding two halves together is an option and in fact at least one fella that has been here and on several other forums has done just that with the 1885 HighWall, he has built more than one that way I think. I have considered this myself, using 8620 alloy with the proper filler and welding process then stress relieved before finial finishing. By doing that the receiver should be nearly as strong, or even equal to, a receiver machined from a solid block. However I decided against it because while it may have saved some time and effort to me it just didn't seem to be worth it, to someone else however it very well may be. Back to your bolt together question, for a RF maybe but personally I would limit it to that.