Artisanal Gunmaking, No compromises, No corners cut, EVER

Wednesday, April 15, 2020

A Hoffman Arms Shotgun

Here's a gun that definitely doesn't come across the bench every day.  Many are familiar with Hoffman Arms Company for their custom bolt-action rifles built on Springfield '03 and Mauser 98 actions but they did also offer shotguns.  The most commonly known Hoffman shotguns were their side-by-sides (in both boxlock and sidelock form) and trap singles, which were most likely bought-in from England in unfinished form.  This one however proves that Frank Hoffman wasn't afraid to try something different.  It's a 20 gauge over/under and, having had it apart, it seems to be one hundred percent American.  The action is unlike anything I've seen before, nothing revolutionary or even avant garde but definitely not a copy of anything else.  Its monobloc barrels use split lumps that (actually) bear in the frame sides, a mid-level bolt, A&D style cocking, Southgate style ejectors and a Parker style doll's head rib extension.  The frame is quite heavy, with the massive width being necessary to house the cocking levers on either side of the lower barrel.  Imagine a Westley Richards Ovundo with fixed locks and a Parker doll's head and you'd be fairly close.  The workmanship is exactly what one would expect from a pre-war American custom gunmaker, which is neither complimentary nor derogatory, just an accurate assessment.  The serial number is a low single digit and if their are any others of its kind, I would doubt that they are identical in very many respects.

"That's all well and good but why is it here?" you say.  Well that's a tale of a manufacturing defect and a "local gunsmith's" over-estimation of his ability.  I'll cover the manufacturing defect first, then deal with Bubba McHack's "repair" work.

The ejectors work on the Southgate over-center principle which involves two moving parts, the tumbler and the spring, and a more elegantly simple system for heaving empty shells over the shooter's shoulder has never been devised.  As simple as the Southgate mechanism is in "firing", it still needs a way to recock the tumblers when the gun is closed.  Some guns use the ejector segments themselves to perform this task, pushing the tumblers back into position as the ejector segments are forced forward by the breechface as the gun is closed.  Others use a separate cocking lever, employing mechanical advantage through the miracle of leverage, to rotate the tumblers as the gun is closed.

Hoffman's design is, at least conceptually, a combination of the two.  There is a plunger situated in the forend iron (one on each side) that pushes the tumbler into the cocked position as the action is closed.  The plunger is situated well above the tumbler pivot and works against the frame just above the action knuckle, so that when it makes contact with the frame as the gun is closed it travels axially in its bore, pushing the tumbler into the cocked position.  It's an ingenious design that combines the simplicity (almost) of no cocking system, with the mechanical advantage of the cocking lever system.  It is a design that works very well, so long as the cocking plungers fit their bores, and that's where the problems begin.  In this gun the plungers were .020" to .025" smaller than their bores in the forend iron, which were .187" diameter.  This amount of play allowed the plungers to cock in their bores and bind, rather than smoothly travel for and aft.  In fact they would bind so badly that even with the ejector tumblers and springs removed, they would hinder the action's closing.  Since the leverage that would normally be employed to rotate the tumblers was now directed against the unsupported vertical portions of the forend iron, something was going to give way.  That something was the right side of the forend iron.

Enter Bubba, the local gunsmiff, who clearly figgered "no problem, I'll just weld 'er up".  Now, having seen this weld (and so will you, shortly), two things become readily apparent:  The first is that he did not anneal the case-hardened forend iron, thus dooming the weld to failure even if he knew how to weld.  The second is that he clearly doesn't know how to weld. At all.

Apparently, showcasing his talents with a TIG torch wasn't enough, because he also exercised his woodworking skillz in repairing the cracked forend wood.  For this trick, he used what is hands down, the absolute worst wood-repair product ever hawked to the trade.  I speak of course of Micro-Bed, a single-component, air-drying "bedding compound" that when dry has the consistency of rubber.  Not old-school Colt handgun grip "hard rubber" mind you, more like bicycle tire soft rubber.  The only thing positive that can be said about it is that it sticks really well, but that's not such a positive when you have to remove it.

Needless to say, this repair was not long-lived, not only due to the "quality" of the weld repair but because the root cause of the break was never addressed.  Since the existing forend iron was beyond salvage, the only course of action was to make a new one, which sounds really easy when you say it fast but there are a number of factors that conspire to complicate the job.  The first is that the new iron must be made to fit the already existing forend wood, left and right ejector mechanisms and frame contours.  The second is that the original forend iron was made in two pieces (shoe and leg) welded together.  The original weld is plainly evident and is one of many clues that this gun is, if not one-of-a kind, still entirely hand-made.  With only one option available to me, I forged ahead.  The first thing was to determine the radius of the action knuckle and the lower barrel channel.  With those numbers and a chunk of 1018, I started blanking out the new forend iron shoe.

Another clue that the gun is hand-made is the fact that NOTHING is symmetrical on either side of the gun's centerline.  Nothing, not the position (or height) of the cocking lever slots, not the external contours, not even the height of the forend iron (one side of the frame is lower than the other).  The fun never ends.

Once the forend iron was blanked out it is welded to the original leg.  The weld was filed flush with a generous radius at the transition from shoe to leg (to minimize stress concentrations).  At that point I could actually fit the iron to the knuckle and the forend lug on the barrel.  Once that was done, I had to adjust each cocking slot so that both hammers reached full-cock at the same time and a few degrees before the barrels reach their stop because those last degrees of travel are reserved for the ejection cycle.

Now that we're back to square one (it should be clear by now that a "cheap" gunsmith really isn't cheap) I can solve the root cause of all of this grief, the cocking plungers.  They are machined and filed from O1 and each side is individually fitted before heat treating.

Both cocking plungers are fitted, so now it's time to fit and time the individual ejector mechanisms so that they trip only after the hammers are cocked and just before the barrels reach their mechanical stop.

The forend iron is off to Geoffroy Gournet for engraving and when it returns, I will color caseharden it and then artificially age the external surfaces to match the frame.  In the interim, I'll work on correcting the poor repairs to the forend wood. 

Before
 After

Forend iron back from Geoffroy Gournet, engraved exactly as the original.

I've case hardened the forend iron and will artificially "wear" the externally visible portions to match the frame.  Next is the inevitable refitting (hard fitting) of the iron to the action and final assembly.
 
The finished forend assembly.






3 comments:

  1. Was the forend cut away for educational purpose and/or did it aid in timing the ejectors?

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    1. As stated in the text, the forend iron was broken. If you are referring to the wood, no, it is not cut away. The forend wood is made in three pieces, top left, top right and a single bottom piece.

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