Newbie--sort of--Joining the Forum--Will be hanging around looking for input

[4575wcf]

Hey All

Okay, here we go.  Career machinist here on the verge of full time retirement.  So far, I own a portable forge that needs a bit of restore, I have two hand blowers, one with the forge one bought separately.   I have a post vise, not great quality that needs some restore.  I have an antique Model A vintage separate garage on the acreage that needs lots of restore, but should make a pretty nice separate shop for my treadle lathe (needs restore), my medium sized anvil, quench tub, racks of tooling etc.   Here is the plan.  I would like to set up a small double barrel shotgun shop here on the place, specializing in buying, selling, and restoring the various medium quality American made shotguns from the past.  I have one shotgun rebuild underway now on another more suitable forum, and several receivers in the incoming rack.  I would like to forge chopper lump barrel halves to join together for these receivers.  In traditional manufacturing, the forging ends up round, solid, 30 inches or so in length with a single bitted axe shape forged into one end.  The two halves, rights and lefts are joined to make a double barrel shotgun assembly.  They are then deep hole drilled, reamed, polished, choked, soldered together and regulated (all machining stuff).  I am interested to know if such an assembly could feasibly be forged and rolled to shape in a small shop on specialized hand operated equipment.  The process would be to machine the full length reverse image of the forging into top and bottom wheels of a rolling mill, then hammer forge, open die forge, and roll a suitable drilled section of annealed 4140 over a proper sized DOM mandrel.  The 4140 section would start out shorter with an oversized hole, then get forged down onto the mandrel, drawn longer, the inside diameter reduced the while until eventually it rolled full length through the rolling mill with the rollers completely closed.  Then straightened, carbide buttons hydraulically pulled through to iron, smooth and work harden the bore.  Then final reaming, honing, choking, {more machine stuff} The DOM offers a center hole in the mandrel to work with should it become stuck, and require drilling out.

Heck of a bunch of work I know, I will be learning to forge as I go.  So--is this plan feasible?  Why or why not?  Improvements?  Thanks guys.

[George N. M.]

Dear 4575,

Welcome aboard.  Glad to have you.  If you put your general location in your profile we will be able to give you better answers to your queries.  A surprising number of answers vary with geographic location.  I'm assuming that you are in the USA but that might or might not be correct.

The forging and shaping process you describe sounds pretty complex and fairly advanced.  One thing to consider is that the maximum area that you can forge at a time is about 3-6" because the metal cools below forging temperature so quickly.  So, any process has to be done in a number of repeated steps on anything longer that a short length.

I suggest that you start with simple projects and work up to more complex things.  You need to learn hammer control, how metal moves under a certain impact, and how the color of the hot metal relates to forgability.  These will vary with the type of steel you are using.  I'm not sure what type of steel you would be using for the shotgun projects but I suspect that it would probably be some sort of medium carbon steel.  This means that you need to know something about intentional and unintentional hardening and tempering of that type of steel.

Blacksmithing can be a fairly easy craft to get into and to start making things but I suspect that what you are proposing is fairly far along the learning curve.

Biggundoctor may have some suggestions since he does quite a bit of gunsmithing.

Again, we're glad to have you here and we LOVE pictures of your shop and projects.

"By hammer and hand all arts do stand."

[4575wcf]

HI George 

Thanks for the welcome.  I updated my profile to give a bit more information as suggested.  The steel used will be cold or hot rolled SAE 4140 round bar.  Sorry to get so wordy with that initial post, I just wanted to establish exactly where it is I want to eventually go with this forging.  The machines and tools required will be built here at home, my welding, forging skills etc. etc. will be picked up and honed by getting the shop equipped and restoring/building the various tools and equipment that I have or will purchase.  My main question is whether forging and rolling a larger tube over a mandrel to draw, lengthen and shape it is practical.  Chopper lump barrels are not commercially made that way, and perhaps there is a very good reason they are not.  By forging a hollow cylinder, I wish to avoid the deep hole drilling process.  I am skilled and trained enough to pull deep hole drilling off, but it requires specialty equipment and expenses I would rather not get into for my purposes.

[BIGGUNDOCTOR]

Faster and easier to drill out than forge to shape. With hot forging it would have to be done in an inert atmosphere to eliminate the scale formation. Trying to keep it hot enough while the rollers are sucking the heat out will also be an issue. To cold roll that shape will require massive tonnage in hydraulic power as well as machine strength.  You could buy a used CNC turning center, or Swiss style for a lot less. The other forging option would be a rotary hammer forge.

Seems like the work would easily exceed the value of the shotguns.  Are you working with solid or pattern welded barrels?  Missing barrels?  May look at making the chopper lump into a monoblock. Cut the old barrels off and solder in new tubes.

[4575wcf]

Hi Biggundoctor

Missing barrels is going to be the norm.  Interesting point on the formation of scale, I read that up to a 20% loss of material due to oxidation can occur.  The chopper lump barrels I see forged in videos are hammered out solid from a billet with a large power hammer.  The main concern then would be scale inside the tube forming around the mandrel?   I would like to be able to find, procure, make one somewhat oversized chopper lump barrel half, rights and lefts, that would cover any shotgun from Winchester 21's and Parkers on down to early Stevens' with the proper machining.  If said barrel half had a rough starting hole through, so much the better.

[BIGGUNDOCTOR]

I would be looking at doing a monoblock and adding tubes.  Even so, that will be a ton of work, so I would hope you are not working for free.  Or scrounge up all of the barrel assemblies you can find, and refit them. I would see, and have bought SxS barrels at gun shows.

 

[4575wcf]

I have thoroughly examined the monobloc method of joining barrels, when I first started my research.  I am capable of building a monoblock for any double, and I own a suitable milling machine.  I prefer the chopper lump method because it is the strongest, safest, and most durable method to join a barrel assembly.  Any of these methods is a lot of work, so there is no point trying to go the easier route because there really isn't one.  I expect to charge for the finished shotguns, and a customer who wants a chopper lump barrel assembly fitted to their pet is going to have to want one really bad.  If I have to go traditional, I will learn to forge out the chopper lump blanks solid with the power hammer and open dies, and then figure out a way to deep hole drill them here at home.  If there is a way to forge them as hollow cylinders at home, even if it is complicated and time consuming, that would be okay.   A method to keep the solid rolls heated to reduce heat loss, and an Argon gas shield for the work--is that something that might make the rolling possible?

[4575wcf]

The other problem is the condition of a barrel set you are likely to turn up.  The hinge pin area is usually going to be worn, and the bites peened through use.  By the time you correct all of these issues and sleeve the thing with new tubes, you have created a marginal barrel assembly at best.  A brand new monobloc with brand new barrels--and you are just as good as Beretta and Browning--and they do come undone.  Rarely, but it can and does happen to all of them.  Chopper lumps barrels with a mechanical fit--such as the Winchester 21--do nothing of the sort.

Edited December 25, 2021 by 4575wcf

[Irondragon Forge ClayWorks]

Welcome aboard and looking forward to see some of your work in this section.

https://www.iforgeiron.com/forum/214-gunsmithing-muskets-flintlocks-etc/

[4575wcf]

Thank you for the welcome Irondragon.  I have been an avid tinker with blackpowder guns for years.  I don't know when you will see any activity from me on the forging end of things, this is new territory.  All the same, with the current state of our country, make do and make your own is the new normal, so that is what we are gonna do.  The old timers did it, some of them knew most of what you needed to know about nearly everything to keep a home place going.  Necessity being the mother of invention. 

[Irondragon Forge ClayWorks]

I've been building and restoring old muzzleloaders for about 60 years now. The last one is an old original German Jaeger. Quite a bit of work because it was a basket case it's now a great shooter.

[4575wcf]

NIce one!  That's a beauty!  I may have found a solution to my chopper lump barrel forging operation.  Looking around online, I did some research on the Belgian Damascus barrel industry when such barrels were the world leaders 1880-WWI.  Other than the fact that I am starting with a shorter drilled tube versus a shorter welded and wrapped spiral tube, the forging process should be the same.  The metal is heated and pressed to shape around the mandrel with the mandrel knocked out between heats, and then finished the same way under the power hammer.  It seems a viable starting point anyway.  A large strong foot operated press with compound leverage seems not too hard to figure out.  Hydraulics is going to be too slow for the process in my opinion.  As others have stated, I need first to get a feel for working the metal so I will need to begin hammer forging chunks of 4140 into tooling and go from there.  Apprentice blacksmiths learned to draw, part off, and head hand wrought nails first, that is probably a good place to start.  Making a cut off hardy for my anvil and a nail header both from 4140 should be good starting projects.