Build Path C — From Scratch (9×19)

Contents

Section	Topic
9	Build Path C — From Scratch (9×19)
· 9.1	The four work packages
· 9.2	Materials (9×19)
· 9.3	The lockwork problem (read before committing)
· 9.4	Operation sequence (shop-floor outline)
· 9.5	Barrel & rifling — the likely farm-out
· 9.6	Fixturing notes
· 9.7	Honest difficulty assessment
· 9.8	References (Vol 9)

This is the volume the lab is for. It is also, honestly, one of the hardest from-scratch handgun builds there is — the C96’s screwless, machined-from-solid lockwork (Vol 2) means parts come off the machine close and are then hand-fit to function. This is a months-long project, not a weekend. Treat the patent as the geometry reference (Vol 2, Vol 6), measure a specimen for the lockwork, and budget the fitting time.

Legal first (Vol 11). Manufacturing a firearm for personal use is federally permitted for a non-prohibited person making a non-NFA gun not for sale, subject to evolving ATF marking/“readily” rules — but several states require serialization/registration or forbid home manufacture. Do not build a select-fire (Schnellfeuer) gun (machine gun; closed under Hughes). Confirm your state before cutting metal. ../../_shared/legal_ethics.md.

9.1 The four work packages

The architecture (Vol 2 §2.3) is the build breakdown:

Package	What	Machines	Difficulty
Receiver	One piece: magazine well + trigger guard + bolt-tunnel rails	CNC mill (multi-setup)	High
Barrel + extension	Barrel and extension as one piece; chamber; sights	Lathe + mill; rifling likely farmed out	High
Lockwork	Hammer, sear, sear lever, locking block, coupling rocker, mainspring/plungers, safety, disconnector	CNC mill + extensive hand-fitting	Very high — the time sink
Bolt, magazine, grips	Square bolt + firing pin/extractor; follower/spring; walnut grips	Mill + lathe; router/mill + 3D print	Medium

9.2 Materials (9×19)

• Stressed parts (barrel extension, bolt, locking block, receiver rails): 4140 (chrome-moly), heat-treated. Confirm the mill spindle/feeds handle 4140 in the section sizes involved (per ../DEVELOPMENT.md; lab catalog TBD).
• Lockwork small parts: tool/carbon steel, hardened and tempered (or 4140), with straw/fire blue on the historically-strawed parts (Vol 10).
• Barrel: a bought-in 9 mm (.355″) 6-groove RH blank, chambered and fit, is the realistic route (Vol 9 §9.5). 1018 is fine only for a non-firing/display build — never for a chambered barrel or stressed part.
• Grips: walnut (Vol 10).

9.3 The lockwork problem (read before committing)

The C96 lockwork is the build. Three realities:

1. Fitting, not bolting. The hammer/sear/locking-block/coupling-rocker interfaces are hand-fit; small geometry errors compound into a gun that won’t lock, won’t disconnect, or won’t take down.
2. Prototype in plastic first. 3D-print the lock sub-frame and internals at size and prove the interlock + the no-pin takedown sequence (Vol 6 §6.3) in PLA/PETG before cutting steel. Iterate the geometry there — it is the cheapest place to get the kinematics right. This is the single highest-value step in the whole build.
3. Two features are non-negotiable: the disconnector (forward-mainspring-guide projection on the sear actuator — without it the gun is full-auto, Vol 6 §6.2) and the takedown-latch/hammer interlock (safety, Vol 2 §2.6). Build both exactly.

9.4 Operation sequence (shop-floor outline)

Expanded from ../DEVELOPMENT.md §5:

1. Acquire reference — patent drawings (geometry/kinematics), a measured specimen or parts set for lockwork tolerances, the dimension table (Vol 6 §6.5).
2. 3D-print prototype the lockwork (and ideally a full one-piece dummy at overall dimensions) — prove interlock, takedown, disconnector, and “feel.” Iterate.
3. CAD the parts in Fusion against the patent geometry, locking the 9×19 chamber/feed (Vol 3).
4. Machine the receiver — multi-setup; the slab sides are forgiving, the magazine-well/rail geometry and the lock-sub-frame slots are the precise features.
5. Barrel + extension — machine the extension; fit the chambered barrel (§9.5); cut/install sights; cut the bolt tunnel, bolt-stop slot, and the locking-block stud.
6. Lockwork — machine each part oversize-to-fit, then hand-fit to function. Expect iteration.
7. Bolt — square, hollow; firing pin + return spring + recoil spring + extractor; the T-grasp.
8. Magazine internals + grips.
9. Heat-treat the stressed parts; headspace with go/no-go.
10. Finish (Vol 10): rust-blue receiver/barrel, straw small parts, oil grips.
11. Mark per Vol 11 — distinct serialization if your jurisdiction requires it; no counterfeit Mauser banner/proofs (Vol 10 §10.6).
12. Function + careful live-fire proof with standard-pressure 9×19; no +P in a freshly fabricated action without formal proof testing (Vol 3 §3.5, Vol 12).

9.5 Barrel & rifling — the likely farm-out

Cutting a quality rifled 9 mm bore is the operation most likely to leave the lab. The realistic options: buy a 9 mm (.355″, 6-groove RH) blank and chamber/fit it to your extension, or have a barrel rebored/rifled by a barrel maker. Confirm in-house rifling capability before promising an in-house barrel (../DEVELOPMENT.md, ../blueprints/README.md). Chamber for 9×19 — short case, mouth-headspacing — not a scaled 7.63 chamber (Vol 3).

9.6 Fixturing notes

• Receiver: plan the setups around the one-piece blank; the round rear section and the internal rail/slot geometry drive the fixture plan. A 4th axis helps the cylindrical features.
• Lockwork: small parts want soft-jaw/fixture-plate work and repeatable datums so the hand-fit iterations stay referenced.
• Barrel extension: a dedicated fixture for the bolt-tunnel/extension features (a known community approach for C96 uppers).

9.7 Honest difficulty assessment

This is not the DL-44 (a Mauser with bolt-on greeblies). A from-scratch functional C96 in 9×19 is a serious machining + fitting project — realistically 100–300+ hours, gated by the lockwork fit and the barrel. A non-firing display version (1018/aluminum, no chamber, no live lockwork) is far easier and a legitimate stepping-stone — and is also the path if you want a prop-donor stand-in rather than a shooter. Decide which you’re building before you start.

9.8 References (Vol 9)

• ../DEVELOPMENT.md §1–7 (build-path matrix, from-scratch workflow, pitfalls).
• Vol 2 (architecture), Vol 6 (mechanics/takedown/dimensions/drawing package), Vol 3 (9×19), Vol 10 (finish), Vol 11 (legal).
• US Patent 584,479 (geometry, public domain, ../blueprints/). Full bibliography: Vol 12.