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I picked up an action recently pretty cheap. Well an action and a stock. No barrels and no forend. I've been playing with the idea of making up a block, and using a couple barrel blanks. I machine injection molds for a living, so I am very familiar with how much work it would be to reverse engineer for this. Lets lean into the idea of doing it rather than discouraging it because its hard. I know its hard. LOL.

I've already waded through a few threads on French shotguns while I was waiting for membership approval. I'm not seeing anything like a parts diagram. What I would really like if somebody would be so kind is to post some decent photographs of the barrel hardware and the forend hardware.

Yes, I checked the usual sources. Numreich, Jack, Sarco, Ebay, Gunbroker and more. Didn't really find much. A couple "shotgun unknown" items might be similar. For this discussion lets please, "lean into the idea of doing it." I may decided not to, but my goal is hopefully to gain more information on parts and only then consider if I want really to machine, solder, and hand fit or not.

Could you post pictures of the action and flats with measurements? The length of the watertable, distance between the firing pins and the way it cocks and how it locks up. Also the diameter of the hinge pin and what the radius of the knuckle are all things you will need to know, and us to help.

There is a book that a guy welds a new lump on a barrel set to fit an action I don't remember what book.if you can machine a lump and you weld it might be a less labour intensive fix.

Welcome to the forum, Bob. Thanks for sharing the info with us, and I wish you the best in your endeavor. I can appreciate your desire to do this. There are some sharp people on here (I do not include myself in that group) concerning gun building. Be patient. Maybe some of the more knowledgeable here will see your post and offer something that will help.

Best wishes on gathering the info to tackle this venture.

Mark II, I will certainly get to that at some point, but right now I am in data seeking mode. At this point I think its unlikely I am going to luck into the right parts, so seeing images of the mating parts I don't have is more useful.

mc, I can reverse engineer and machine. I can shoot metal out of a hot glue gun for metal. Sometimes it looks good, and sometimes it looks like what comes out of the north end of a south bound chicken. I have considered the approach of cutting off and welding on hardware to some other barrel set, but if I build from scratch I think most barrels are silver soldered together. Also within my skillset, although I am no master at it.

Stanton Hillis, Thank you. I am sure there are.

skeettx, I missed your armslist link when I first read your post last night. That looks like exactly the same shotgun. The forum link you posted is actually the first thing I saw when I first visited this forum from a search engine result for the first time. I have not read every word of every post in it, but I will. I have skimmed every post, read many of them, and looked at some of the images.

Thank you all for your help.

Bob;

Are you asking for help for making a "block" that will have the lumps machined into it and also where you can add barrel blanks to this block? If that is what you are asking and if you have a vertical milling machine you can build what is known as a shoelump style "block" to do what you desire. Look down through this old post (see link below) of work I did some years back in building a shoe lump barrel set. You could machine such a shoelump block in plastic as a prototype.

Kindest regards;
Stephen Howell

http://forums.nitroexpress.com/show...al&topic=&Search=true#Post297834

Bob,
First of all, Stephen Howell did(does) fantastic work and I am not denigrating it at all, but I believe you will find it much easier to make a Monoblock instead of shoe lump type block. The obvious difference between the two types is that with a Monoblock, the barrels are inserted into the Monoblock and the "joint is large enough that soft solder is sufficient to hold them, avoiding the possibility of overheating the barrels. The often-voiced objection is that there is sometimes a visible joint, but not everyone finds this objectionable. If you can remove the hinge pin, and locking blocks, the receiver will tell you the dimensions you need to mill the Monoblock. I believe barrel blanks already prepared for use with a Monoblock are available as a special order from Walther. The diameter of the holes in the Monoblock should be determined from the end of the barrel blank.
Mike

bushveld, I looked at the first page of your thread on the other forum and noted the use of a D-bit in your pictures. That made me smile a little. I've been learning to make my own single lip cutters for special applications to reduce the number of setups for some jobs. Special dovetails for tool holders, angled faces that can be programmed flat in a cnc mill instead of tilted in a sine vise, etc, Stuff like that. I make such tools out of broken carbide, because, well I have a lot of broken carbide. LOL. I do have a vertical mill or two or three or ... well 5 currently in regular service. Another one for only those emergency repairs on a day when I have a broken air compressor, and one more that had a catastrophic ball screw failure I haven't gotten around to fixing yet. Even a small one still in the crate I bought just to do a video series I haven't started yet. I think that makes nine including the retired one on a shelf. They range from toy to light industrial in size (2 tons). No really big machines. I might have a lathe or two as well. I make a living using them. Someday I might get good at it. I just read a few of your posts in that thread and I can see where there will be a great deal of good information in it. Thank you.

Der Ami, Thank you. When you say soft solder I have to assume you atleast mean plumbers solder. I can't imagine using 60/40 unless it was just to gently hold pieces that are mechanically wedged in place... and yes I can see how the barrels might be mechanically wedged into a mono block. Or atleast what I picture in my head as a mono block.

I'm certainly not certain of exactly how I will tackle it just yet. I might even have a fantasy of just lucking into the parts... like fantasizing about winning the lottery.

Bob,
As I recall, it was 50/50 solder. The Monoblock/barrel solder joint was large enough that it was plenty strong enough to hold them together. My experience with this was in the mid 1970s to early 1980s. I highly suspect that now they would use a high strength glue such as Loc-Tite bearing fixer (I think it is their #662 or 668). I recently lost a friend that converted double shotguns to double rifles, using this glue. Due to a mistake, he had the need to break the bond of this glue and he had to heat the barrels/block to bright red to do it. With regard to machinery, you would be surprised how little was required. My German gunsmith friends used only a small "speed lathe" that had a shop-made bed extension when replacing barrels using the old ones to make the "block" ( hakenstuck?). This lathe had no carriage or lead screw. This was before reunification and if they made a new barrel set for an East German gun that no blank sets were available for (Merkel, etc.) The used a small horizonal spindle mill that had a vertical spindle attachment installed. The main "tool" was their experience and skill. To put the parts( monoblock/barrel tubes, ribs) together, they sent them to the barrelmaker( rohermaker?) who had the appropriate equipment (oven). Even though my friend was qualified to fit the new barrels up, he usually called another friend in to do it. This fitter used mostly files and scrapers to fit the barrels in. He filed like a machine and worked right on top of thousands of dollars' worth of engraving without "missing a lick". His main equipment was also his skill.
If you take the project on and mess it up so badly that you can't sell the parts for scrap iron, you still would not have lost enough to outweigh the fun and experience you would have gained.
Mike

To be clear: When you say mono block you are referring to a part that completely encircles part of the chambers of the barrels right? If so, depending on the shape of the barrels mechanical wedging might be taking all the force, and the solder just keeps them from falling out if you bump the barrels with the action open. Sure there is more surface area, but a tapered fit is incredibly strong.

I might own a file or 40, but I try very hard not to need them. That being said I use them at the lathe every day. Well everyday that I use one of the lathes. I hate file work. I recall my dad making me try to file hardened steel a gazillion years ago. The parts I'd make for this would likely be 4140HT (because I have it on hand), and while it is fileable its not fun if you have to remove much.

Bob,
Yes, that is what I mean, the barrel blanks are inserted from the front and there is a "shoulder" that bumps against the block. The "tenon"(for want of a better word) including the chamber is straight, not tapered. Here, some people thread the parts, but this is not necessary. I am a poor filer and am in awe of the abilities of the gunmakers in Germany, at that time. The barrel fitter I mentioned even polished with a file. It was a very fine cut file and he loaded it with chalk, which he oiled. If they were making a new gun, they did a significant part of the receiver shaping with chisels as well as files. When I go into the websites of these same companies, the sons and grandsons of the ones I knew have all gone to CNC machines for most of the work. Files would still be used for a lot of the finishing work. I always wondered how they fit the side clips on pre-war guns and one of my friends told me he was an apprentice in his grandfather's factory (Meffert) in 1938, with the job of peining the side clips. His description told me the barrels were machined in the area and the actual side clips were formed by moving the metal into the area by hammer. Now it makes sense.
Mike

I bought a couple barrels the other day. They are NOT setup for this and they already each (single barrels) have some hardware on them for some other gun, but they look like they were pre machined to fit into a mono block. Okay, I bought them because they were cheap. Cheaper than the action. They are a little shorter than I would like at 23 inches and change, but I once hunted birds with a guy who was using a choked 18.5in pump. He did okay. I hope they have some kind of choke, but if not I guess I'll spend way more money than they are worth to turn, ream, and thread for choke tubes. I hope I can get the prefit hardware off of them and not look to bad, or at least position it to hide under the forehand. I'm not sure from the description if they have even been chamber reamed. It might be time to start hunting for a 16ga chamber reamer to go with my 20.

Bob,
It's not for sale, but I have a 16 ga. long forcing cone reamer. If you get to that point, you can arrange to borrow it. BTW, One of the best decisions I made was having Heym make a set of open choke 60cm (23" and change) barrels for my 16 ga o/u. I had them made for Bob Whites but use them for all small game. I wouldn't worry about choke tubes.
Mike

That's downright generous of you. I might take you up on it.

It might also be an opportunity to see if a D-Bit reamer would do for those of us who might only ream one or two of something. Yeah, probably not, but I'll ponder on it a while.

Bob,
D bit (we used to call them half reamers) reamers are slow but work well. I have made a couple with satisfaction; you have to watch the "relief" at the diameter changes. You also have to grind them in half (not the pilot) after hardening, to prevent warping.
Mike

I've made a few d-bit cutters out of solid carbide using a diamond wheel. No warping. LOL.

Yeah, I know. A piece of carbide big enough for a 16ga reamer would probably cost as much as a finished HSS reamer. Also my little TC grinder doesn't have the range to make a tool that big. I do have a surface grinder, but that's not as easy (for me) to make round cutting tools on. Okay, maybe mostly because I just haven't used it that way. I'm having visions of setups dancing in my head like its Christmas Eve.

Dang-it. Now I want to do it just to see if I can.

One thing I found is sometimes I just have to get in there and grind a relief by hand anyway. I made an 18 degree (144 degree included angle) chamfer tool the other day, and that was the only way I could remove the heel easily. Like back relieving the heel free handing drill bits on the bench grinder.

The thing about half reamers is you can make them with simple equipment. I made my first one using a lathe, propane torch, a magnet, my wife's oven( she wasn't at home), a bench grinder, micrometer, and stones. Later, I made a TP grinder, which helped a lot. I'm sure a propane torch wouldn't be hot enough to make a 16 ga reamer. Ruined carbide tools can be very helpful in making other tools, such as boring bars, half reamers (shanks are already useable diameters), etc. Diamond wheels are great if you have them, but absent them, a "green wheel" will work. Since my shop was in the basement, I used water hardening steel to not generate oil quenching smells in the house. A happy wife means a happy life(57 years going on 58). It helps if you have a friend that owns a scrap yard in an area with several machine shops that bring "drops" and old cutters/tooling in, the drops are often the ends that still have the identifying color code intact.
Mike

Of course you can cut your rough profile ahead of time on the lathe too when working with W1/silver steel.

Unfortunately, I pretty much have to buy all of my metal from metal vendors.

Both fortunately, and unfortunately I have lots of broken carbide end mills in a bucket for making tools out of.

I do have a project I want to make that is a nice small scale practice analog. A common mold type I make is hinged at one end for casting low temperature melt alloys. Usually I do all the complicated machining on one of the CNC Mills, and then I do basic stuff like drill and tap for handles and drill for the hinge pins on one of the manual milling machines. The hinge pins generally take three drills. The friction size, the free slip size, and a chamfer. The bosses that form the hinge have a uniform thickness size and a multi diameter drill might be faster than sticking three different drills in a chuck on both sides of the mold. Ideally it would be a twist drill, but a d-bit might still be marginally faster than stopping the spindle and changing drills three times for each side of the mold. If it works out at all I might get ahold of rogue .systems Inc and ask them to make me some custom split point drills in carbide.

I am curious to know how many people are actually interested in this thread and hoping to see build notes and build pictures if/as I progress through it.

I suspect you will find more interest once you start work and post photos.
Mike

That is likely true, but people who want to see something like that need to bear in mind documenting and photographing is a process in and of itself. Often I do things in the shop that some people would love to see but it often takes longer to do that than it does to just do it. Video even more so.

Post your progress and see what happens,

It is always nice to see a good build thread.

I have had to use old shotgun barrels to sleeve sxs,I try and find a set of cast off double barrels that are at least mid 20th century steel they are soft soldered and brazed at the breech also you end up with ribs,Belgian barrels sometime have the ribs brazed I think some Stevens have brazed ribs.good luck on you project .im up in showlow

Bob,
If you take mc's example, I suggest you go to the Walther website, I think you can find the German standard and tested dimensions for turning the chamber end of the barrels. At the same time you can " pick out" the diameter of the reamer you will need for the final sizing of the holes in the monoblock.
Mike

My folks have a place in a park up in Show Low where they spend their summers. Same name.

I found some loose singles for an O/U. They were pretty cheap so... They have some kind of rib already on them, but it looks funky. Like something I'll have to remove. I got the impression they were new old stock, (never installed) but that leaves me wondering why they are only a little over 23". The breach is already turned for a mono block, but it says the chambers are short. That might mean for 2-1/2 shells or it might mean unfinished. The tracking shows they arrive today along with the new buffer pad for my Buck Mark, so I'll have a look today or tomorrow.

The box is here:



They were well protected:
The box was very stiff double layer, and the barrels were well padded inside:


They look new, if they have some very minor surface rust from a long time on the shelf:


The machining for the chambers end to fit into a block looks decent, and sharp:
Those ribs make no sense to me, but as long as they don't fall off from soldering other things I might be able to just turn them to the bottom and design my forend lug to fit between them. I'll be making my own forend anyway so it can be anyway I choose.

Heat up the rib and see if it falls off . I have been looking for barrels like that only 30 inch or more

You can use conduit for the bottom rib. Cut and fit anf remove the outer coating and solder it on.

That's what I first thought. I may still try that. I have lots of projects so I can take my time thinking about this one, and I can get more barrels if I screw them up. They were cheap... unless somebody buys them all.



What is the significance of that? I know about removing the zinc galvanizing on galvanized metal because zinc fumes are toxic, but what is the benefit of using conduit? Why is it better than just soldering on a fitted steel rib on the top and bottom? Remember I have a small CNC (and manual) machine shop so I can make parts, and I have mentioned I have steel on hand.

Emt

Emt is cheep thin easy to cut for the bottom rib ,the top is more difficult to make it should be hollow to save weight .english guns had the ribbe's tinned on using pure tin ,tin with lead flows a lot easier I was told the reason pure tin was used is that it expand and contracted similar to steel,used in barrels .

I didn't think the weight would be a big deal. My preferred hunters for years have rotated through full size 12ga Rem 870, Moss 500, and Win 1200 pumps. I think they are all heavier than or at least as heavy as this gun will wind up. I do have two other doubles. An old 410 (1920s likely) and a KBI O/U 12 (Russian Bakal). The KBI feels a little heavy, but the 410 is almost to light. Neither bothers me to hold all afternoon on a slow hunt.

Of course I do see the benefit of a lighter shotgun when the birds are coming fast and furious. It was brought home to me the year my son handed me his 1300 youth model and took away my 870 Express Magnum. I had been hitting well, but he had been struggling. When he took the 870s he started hitting. The 1300 came on target so fast for me the hunt was over for me almost before it began. He was hitting, but I had to stand and point because my hunt was done.

P.S. Off Topic: Having owned multiples (at different times) of those pumps I feel the 500 is generally and by far the best built of the 3, but the 1200 is my favorite to shoot.

P.P.S. Also Off Topic: I've got more then a few misc shotguns. I think the oldest is an Iver Johnson single in the project safe.

The weight savings from a hollow rib not only affects the overall weight, but also the balance.
Mike

Der Ami & MC;

When I need rib material for side x side guns and rifles I decide upon the contour of the of the rib that I want and the wall thickness and then calculate the diameter of a steel tube that has that or near that contour, (say 2 inches diameter) and then I buy (usually from eBay--although it will sometimes take a day or two to find someone selling it) seamless thin wall high strength tube lengths (say .049" wall thickness) that are scrap from the shops of automobile race car builders. I think all of the times that I have purchased these tubes it has been from some of the North Carolina race car building shops. Really nice and very thin wall "stuff".

Kindest Regards;
Stephen Howell

bushveld,
My comment applied to the top rib, do you also use thin wall tubing for them?
Mike

Yes. The size that I like is 1 -7/8 inch O.D. chrome moly alloy steel with .035 inch wall thickness.

Kindest Regards;
Stephen Howell

Interesting. I hadn't really thought weight was a huge deal. Particularly what could not be more than a couple ounces. I'll do some CAD and math later. My CAD software will give me the exact CI or CC of any solid model part. From there its simple mass X volume.

I was actually considering something more substantial on top. Functionally the equivalent of a modern raised rib. I don't have the skill to wire barrels together and regulate them like a real shotgun builder, by actually shooting them. I was thinking of just doing the layout in CAD, do little math, and set them up with blocks and fixtures so the theoretical center of the pattern should coincide at about 40 yards. Of course the machines (or myself) probably aren't capable of making the fixtures to that level of precision anyway, but... I planned to try.

Well, none of that today. I'm in the shop finishing up some custom fishing lure molds so I can get them shipped on Monday.

In theory if you bore the monobloc for the barrels so the barrels touch at the muzzles and the center of the bores are level you will be really close.

You want to explain that to me? They would be tapered inwards in relation to each other by a couple degrees just due to the outer profiles of the barrels. If each barrel is angled towards center just 1 degree (2 degrees included angle) the center line of the theoretical perfect pattern will be offset to the other side about 2 feet at 40 yards. The patterns might overlap at 40 yards, but the center of the patterns would be four feet apart. I would say, "if I did the math right," but I used a triangle calculator on my cell phone. If the ap did the math right.

My plan was to basically bore the block and make spacers such that the center line of the chamber was almost exactly the same distance apart as the center line of the muzzle.

P.S. I've been playing with the idea of using a clamshell design as opposed to a one piece mono block. It would simplify some of the setup issues for machining. I'll probably cut a mono block anyway, but I've got to setup and figure out the basic geometry and do some basic plans before I decide the best approach for me. The center line of the chambers is restricted by the firing pin locations on the frame.

Bob, I am given to understand that it is more than a math problem, the effect of the shooters body and "hold" affects the point of impact and is very difficult calculate. Granted, this is likely easier to see with a double rifle than a shotgun, but it is still there. Milling the rear part of the top rib is often done as you described. One thing I recall and didn't mention is when drilling the holes for the barrels in the monoblock, they would leave one of them smaller than the other. This is to give them the ability to move it slightly, if final measurements show movement is necessary.
Mike

There is also the effect of recoil that moves the movement laterally and slightly down. If you have access to other barrel sets you can measure the center of the breach and the center of the muzzles and find the basic angles. When relaying ribs I use a jig that has level surfaces to lay the barrels on so the center of the bores are parallel at the muzzle. That leaves the patterns vertically, and the angles of convergence will overlap the patterns horizontally. The rub comes in the fact if you just bore sight the barrels you may not get where you want. They may appear to crossfire sooner than you want .

I only have two other doubles. One is an OU and the first barrel tends to shoot a little low. The second shoots dead on. Both are centered. The other is a .410 side by side. One barrel shoots a little low left. Second barrel shoots dead on. This is based on fixed patterning with a sheet of butcher paper stretched between two posts. If I adjust I can hit with them in the field.

Haven't done a darn thing with this in two months. I've just been sort of thinking my way through it. More and more I like the idea of a mono block, but fitting the barrel lump seems like it could be its own issue. Would it be strong enough to make a mono block for the barrels and the barrel lump that engages the frame separately and bolt and solder them together? I think if it is made with just the right tolerance the recoil force will all be on the faces of the frame, not on the barrel lump.

The circle on the lump is fitted to distribute recoil and help keep it on face.look up joining a sxs on the internet also the book guncraft has a good explanation.