Building a Working Reproduction: From Parts and From Scratch

7.1 Before anything: the legal line

A flintlock reproduction of the Puckle gun that uses black powder and loose projectiles is, on the federal statute’s plain text, an antique-firearm replica and outside the Gun Control Act and the National Firearms Act; Michigan still treats it as a firearm for most purposes (Volume 8). Two things would take a build outside that and are not part of this volume in any form:

• Any chamber, chamber set or conversion designed for fixed ammunition or modern primers. That ends the antique-replica status, and with a bore over half an inch the gun would also be a destructive device (Volume 8).
• Explosive projectiles. The print’s “Granado Shells” are destructive devices in their own right, federal and Michigan, whatever fires them.

Black powder, a flint, round ball and cast lead cubes: nothing else.

7.2 No kit, no drawings

No kit, plans set, or commercial reproduction of the Puckle gun was found for sale. The one modern gun described in print, the Belgian gun bought “and the plans” by an American collector in 2014, came with plans the maker’s widow sold privately (Volume 3); they are not published.¹ No dimensioned drawing of any original was found. The published dimensions for complete guns are those in Volume 3:

Table 1 — No kit, plans set, or commercial reproduction of the Puckle gun was found for sale. The one modern gun described in print, the Belgian gun bought "and the plans" by an American collector in 2014, came with plans the maker's widow sold privately (Volume 3); they are not published.[^asac] No dimensioned drawing of any original was found. The published dimensions for complete guns are those in Volume 3

Gun	Barrel	Bore	Chambers	Weight
St Petersburg (bronze)	100 cm	28 mm	9	52.9 kg
Beijing	92 cm	4 cm (barrel), 2.5 cm (chambers)	11, each 11.5 cm long	not stated
Common English summary (unsourced)	3 ft	1.25 in	6 to 11	not stated

Everything else has to be scaled from the 1718 print and from photographs. The print carries a scale bar marked 1, 2, 3 without a unit; if it is in feet, the barrel on the print is close to three feet, which may be where the common “3-foot barrel” figure began. That is an inference and should be checked against the St Petersburg gun’s 100 cm before being relied on.

7.3 Decisions to make first

1. Firing reproduction or non-firing model. A non-firing model in plastic, aluminium or wood proves the mount, the screw, the index stop and the pan covers with no pressure vessel anywhere. It is the right first build whatever comes next. A model that is not designed to fire and cannot readily be made to is not a “firearm” under the federal or Michigan definitions (Volume 8).
2. Which gun to copy. St Petersburg, Beijing, or the print. They differ (above), and a reproduction should say which it follows.
3. Full scale or reduced. A full-size bronze gun weighs over 50 kg. A reduced-scale gun built round a commercial muzzleloading barrel is cheaper, lighter and safer, and is still a working Puckle in every mechanical respect.
4. Round or square chambers, or both. The interesting build is a square-chambered set as well as a round one, because the square set is the one that survives at Boughton and the one nobody has fired on record.
5. Brass or steel. The specification says “Steel Iron & Brass”; the survivors are brass, bronze and iron. A firing reproduction’s pressure parts should be steel (below); brass and bronze belong on the parts that carry no pressure, unless a builder has the metallurgy and the proof to justify a bronze barrel.

7.4 Choosing a pattern and a bore

The bore drives everything. Three practical choices:

• About 28 mm (1.1 in), the St Petersburg gun. Full scale. A round lead ball of 28 mm weighs about 130 g (4.6 oz), worked out here from the sphere’s volume and lead’s density of 11.34 g/cm³. A heavy, expensive, slow build with no commercial barrel at that size in steel found for this dive.
• About 1.05 in, a commercial 4-bore. The hub’s Stonewall Creek blunderbuss dive, Volume 2 documents a 4-bore brass smoothbore barrel of about 1.052 in bore from one specialist maker, in very short supply. Close to full scale, but brass, belled for a blunderbuss, and plugged at the breech; it would need re-working and the maker’s agreement that it suits a different gun.
• Reduced scale on a standard muzzleloading bore, .62 to .75 in (20 to 12 bore), for which smoothbore barrels are made in steel and loads are published. The hub’s Blunderbuss Kits Compared, Volume 3 records a .75-calibre smoothbore barrel sold as a component. This is the sensible first firing build.

The rest of this volume is written for the reduced-scale steel build and notes where full scale changes things.

7.5 Path A: from bought-in parts

There is no parts kit, so “from parts” means buying the parts that the muzzleloading trade makes and making the rest:

Table 2 — There is no parts kit, so "from parts" means buying the parts that the muzzleloading trade makes and making the rest

Part	Bought in	Notes
Barrel	A smoothbore muzzleloading barrel blank in steel, in the chosen bore, without a breech plug	The breech must be open; the chamber nose seats in it
Lock	A commercial flintlock lock from the muzzleloader trade	The hub’s blunderbuss dives cover the round-face English locks (Chambers/Calvary, L&R) and their tuning: Stonewall Creek, Volume 3
Flints, mainspring spares	Muzzleloader suppliers	—
Bullet mould	A commercial round-ball mould in the chosen bore	Key 21 on the print is a bullet mould
Everything else	Made	Chamber sets, axis, crane, elevating arc, tripod, pan covers, cube mould

A commercial lock is built to sit in a wooden stock, its pan against a barrel’s vent. On a Puckle the lock sits on the breech above the chamber set and fires a pan that belongs to the chamber, not the barrel (Volume 4). A bought lock will need its pan removed and its steel re-arranged so the flint strikes over the pan of the chamber in line. That is the main engineering task of Path A.

7.6 Path B: from scratch

Everything made, including the lock and the barrel. The barrel is the reason to think hard: boring and finishing a 90 cm or longer smoothbore barrel needs a deep-hole drilling set-up or a gun drill and a lathe with the bed length to support it, and a short-bed hobby lathe cannot do it. Bought-in barrel blanks are the norm even in from-scratch builds. A from-scratch lock is a standard flintlock project: lockplate, cock, tumbler, sear, mainspring, sear spring, frizzen spring and steel, with the springs and the steel hardened and tempered. If the shop has no heat-treat oven, springs and the steel go out to a heat-treat shop or are bought.

What separates a scratch-built Puckle from any other flintlock is the chamber set, the screw and the index stop; those are the same on both paths.

7.7 The work packages

In the order they depend on one another:

1. Choose bore and pattern; print-scale drawings. Scale the print and the photographs to the chosen bore; check every proportion against the St Petersburg and Beijing figures.
2. Non-firing model of the axis, screw, chamber set, index stop and crane (printed plastic is enough).
3. Barrel: bought or made; breech seat cut.
4. Axis and screw, fixed to the barrel’s breech assembly.
5. Chamber sets: at least two, round; optionally one square.
6. Pans and covers on each chamber set.
7. Lock on the breech.
8. Crane, elevating arc, centre tube, tripod.
9. Inspection and proof (below).

7.8 The barrel and its breech seat

The barrel is a straight smoothbore tube, open at both ends. At the breech, cut a seat for the chamber nose: a counterbore concentric with the bore, of the nose’s diameter, a few millimetres deep, with a square shoulder for the nose to bear on (the print’s stepped chamber nose implies a shoulder; a taper is the alternative that Wikipedia’s description suggests). Bore and seat must be concentric to the axis of the chamber set’s screw; set them up together, not separately.

The seat is the joint that holds the gas. Its depth sets how far the chamber set must move along the screw to clear it before turning (Volume 4, step 2). Keep it shallow: every millimetre of seat depth is a millimetre of screw travel on every shot.

7.9 The chamber set

Puckle’s sets were built up: short tubes fixed round a hollow centre on a back plate.²³ A reproduction can follow that construction or machine the set from one piece of steel.

• Built-up: each chamber turned as a separate closed-ended tube with its nose, vent and pan seat, then fixed to a centre and back plate. Easier to make square chambers and to replace one damaged chamber; harder to get all the chamber axes on one pitch circle and parallel to the screw.
• Machined from solid: one round blank, chambers bored on a pitch circle on a CNC mill with an indexer, as for any revolver cylinder (the LeMat dive, Volume 8, describes the operations). Stronger and more accurate; square chambers in a solid block need EDM or broaching.

Either way:

• Chamber walls: no thinner than the barrel’s own wall at the breech for the same bore, which is the one wall thickness a muzzleloading barrel maker has already proved for that bore. Check it on the model and on the part.
• Closed rear end with a vent drilled to the pan.
• Nose turned to fit the barrel’s seat.
• Chamber length enough for the charge, the projectile and a wad, and no more.
• Number and mark every chamber and every set.

7.10 Square chambers: the geometry a cube imposes

A cube leaving a square chamber has to enter a round bore. Its largest cross-section that the bore must pass is the square face, whose diagonal is the side times the square root of two. For the cube to pass a round bore of diameter D, the cube’s side must be no more than about 0.707 D. (This is plain geometry, worked out for this dive; it is not in any period source.)

So for a round bore of 0.75 in, a square chamber and its cube can be no bigger than about 0.53 in on a side, and the chamber’s nose must taper from square to round so the cube enters the bore without catching. A cube larger than that will jam at the breech, and a jammed projectile in front of a charge is a burst barrel. The print’s square chambers (item 18) are drawn with the same stepped nose as the round ones; how the original transition was made is not recorded.

Cubes can be cast in a two-part mould machined for the purpose, which is what the print’s item 21 (a mould for casting single bullets) suggests for the round ball. A cube that passes freely will rattle down the bore and fly tumbling. That is expected: the square set is a demonstration of the 1718 design, not a target arm.

7.11 The axis, the screw and the index stop

The screw is the part with no modern precedent in black-powder revolvers.

• Thread: coarse, single-start, and long enough to carry the set’s full travel (seat depth plus clearance) with plenty of engagement left when the set is screwed home. A coarse thread tolerates fouling (Volume 6).
• Clamping: the set is screwed home against the barrel seat; the thread takes the firing load that tries to push the chamber back. Size the thread for that load with a generous margin, and use a hardened steel axis.
• Index stop: something must stop each chamber exactly in line with the bore before the set is screwed home. The Boughton set’s toothed centre is the likeliest original solution (Volume 4). A spring detent in the back plate engaging notches, or pins on the set engaging a fixed stop, are the obvious reproductions. Whatever is used, the alignment check in Volume 6 decides whether it works.
• Crank: a handle on the end of the axis or on the set’s centre, as the print and photographs show.

7.12 Pans, covers and the lock

Each chamber needs its own pan and its own hinged cover (Volume 4).

• Pans on the rear of each chamber, at its vent, all at the same radius so that the one in line sits under the lock’s flint path.
• Covers hinged, with a light spring or detent to keep them shut; they are the chain-fire barrier.
• Lock: on the breech above the set, its steel positioned over the pan of the chamber in line. Whether the falling cock should also open that chamber’s cover, or the cover is opened by hand, is a design choice; the reported original solution is a stud that opens the next pan as the set is turned (Volume 4, unconfirmed). A hand-opened cover is simpler and safer for a first build: no pan is ever open except the one about to fire.

7.13 Crane, elevating arc and tripod

The mount must carry a gun of perhaps 15 to 50 kg (depending on scale) and absorb its recoil without the tripod walking.

• Centre tube vertical, with the crane’s pin turning in it for traverse.
• Crane curved to carry the gun’s weight and leave room for the chamber set and crank behind the barrel.
• Elevating arc toothed, with a catch, as the St Petersburg gun’s “arc-shaped iron elevating stand with teeth”.⁴
• Tripod with a chain between the legs and stretchers lower down, all three on the print and every survivor. Spread the legs wide; a narrow tripod under a heavy gun fired at elevation will tip.

7.14 Materials and finish

Table 3 — Materials and finish

Part	Original	Reproduction	Why
Barrel	Brass or bronze (Boughton, St Petersburg); iron (Buckler’s Hard)	Steel muzzleloading barrel	Known material, known wall for the bore
Chambers	Brass tubes on an iron plate (Boughton)	Steel	They are the pressure vessels
Axis and screw	Iron (not described)	Hardened steel	Thread load and wear
Crane, arc, tube	Iron	Steel	—
Tripod	”Wood & Iron” (spec.)	Steel or wood and steel	—
Pan covers	Brass or copper (Boughton, from the photograph)	Brass	Non-sparking, easy to work

Brass furniture can be finished bright or patinated; steel browned. The Stonewall Creek dive covers brass and steel finishing for a black-powder arm.

7.15 Inspection before any firing

There is no American proof house and no published proof standard for a home-built black-powder gun of this type. Before any live firing:

1. Material records for the barrel and every chamber set.
2. Dimensional check of every chamber against the model; wall thickness at every chamber, in particular between adjacent chambers.
3. Chamber-to-bore alignment at every index position of every set, with a close-fitting rod through the barrel (Volume 6).
4. Seat and nose fit: each chamber’s nose fully seated when the set is screwed home, at every position.
5. Thread engagement at the screwed-home position.
6. Projectile clearance: every ball and every cube passes the barrel freely.
7. Pan covers close and stay closed; the lock sparks over the pan in line.
8. Crack check of chambers and barrel breech after any heat treatment.
9. An experienced black-powder gunsmith inspects the finished gun before it is fired.

7.16 First firing

• Fire remotely. The gun on its tripod, the tripod weighted or staked, behind cover, a lanyard on the trigger.
• One chamber loaded in the set for the first shots, the others empty and their covers closed. Then two adjacent chambers, then a full set. Inspect after each stage: nose, seat, thread, chamber walls, the front face of the set.
• Charges. No published load exists for any Puckle gun. Start below the lightest published load for a commercial smoothbore of the same bore, and do not exceed the heaviest; that is a reference for a different gun, not a licence.
• Look for flash and fouling at the joint and on the neighbouring chamber mouths after every shot. Fouling on a neighbour’s mouth is the chain-fire warning.
• Black powder only. Never smokeless, in any quantity (Volume 8).

7.17 Honest difficulty assessment

The lock and the mount are ordinary black-powder work. What makes the Puckle hard is the combination the 1718 design never had to prove under any proof regime: several chamber sets, each with every chamber aligned to one bore through a screw and an index stop, sealed by a nose in a seat, primed from separate pans next to one another. Expect the non-firing model to change the design more than once. A reduced-scale steel gun on a commercial barrel is a realistic project for a shop with a CNC mill and indexer, a lathe and outside heat treatment. A full-scale bronze reproduction is a foundry project, and its barrel and chambers would need an engineer’s analysis before anyone fired it.

7.18 What could not be verified

• Any dimensioned drawing of an original gun.
• The unit of the print’s scale bar.
• The original index-stop and pan-cover mechanisms (Volume 4).
• Any commercial kit or reproduction currently offered.
• Any published load for a Puckle-pattern gun.

References

Footnotes

1. Joseph McClain, “The First Patent Machine Gun – The Puckle Gun”, American Society of Arms Collectors Bulletin 126, pp. 64–67, https://americansocietyofarmscollectors.org/wp-content/uploads/2023/10/McCLAIN-the-first-patent-machnie-gun-the-Puckle-gun-v126.pdf, accessed 19 October 2026. ↩

2. Patents for Inventions. Abridgments of Specifications relating to Fire-arms and other Weapons, Ammunition, and Accoutrements (Great Seal Patent Office, 1859), p. 26. https://archive.org/details/patentsforinven04offigoog, accessed 19 October 2026. ↩

3. Paul Wilcock, “The Armoury of His Grace the Duke of Buccleuch and Queensberry”, Arms & Armour 9, no. 2 (2012); author’s version, http://eprints.hud.ac.uk/17394/1/BUCCLEUCH_PROJECT_Royal_Armouries_version_2_5_FinalProofEDIT.pdf, p. 6, accessed 19 October 2026. ↩

4. S. V. Yefimov, Voenno-istoricheskii zhurnal, 2019, no. 2 (in Russian), https://cyberleninka.ru/article/n/skorostrelnye-artilleriyskie-orudiya-pervoy-poloviny-xviii-veka-v-sobranii-voenno-istoricheskogo-muzeya-artillerii-inzhenernyh, accessed 19 October 2026. ↩