For precise reassembly or troubleshooting, reference the official exploded view schematic for the G2 model–this document is typically packaged with factory manuals under section 4.2 (“Barrel Group Disassembly”). The firing pin assembly, identified by part code 10-081-00, must align flush with the breech face recess (0.015-inch tolerance) to prevent light strikes. Barrel-to-frame indexing relies on a dual-pin system; incorrect seating of the rear pivot (code 10-034-00) will misalign the chamber by 0.020–0.030 inches, causing extraction failures.
Lubrication points require synthetic gun oil (MIL-PRF-63460) applied sparingly to the action rods and trigger mechanism–excess compound attracts fouling, increasing the risk of sear drag. The forearm bushing (part 10-070-00) should rotate freely with 1–2 pounds of finger pressure; binding indicates deformed threads or improper installation of the forearm lock nut. Inspect the extractor claw (code 10-025-00) for microscopic cracks–these develop under 800–1,200 rounds of +P ammunition and necessitate replacement.
Stock attachment screws (10-052-00) require a torque of 35–40 inch-pounds; overtightening strips the synthetic insert, while under-torque causes action wobble. The pivoting breechblock operates on a 90-degree arc–verify smooth rotation by removing the hammer and cycling manually. Frame rails exhibiting lateral play exceeding 0.003 inches (measured with a feeler gauge) demand shim installation between the grip panels and frame to restore rigidity.
Exploded View Reference for Custom Single-Shot Firearms
Begin your repair or customization by identifying the firing mechanism assembly–locate the striker block (#14) and mainspring (#15) first. These components interact under precise tension; mismanagement risks misfires or damage. Measure spring compression at 3.2–3.5 lbs for optimal ignition reliability across .223 to .45-70 calibers.
Examine the barrel interface (#5) for micro-fractures near the locking lugs. Replace if visible wear exceeds 0.1mm; even minor deformation degrades accuracy. For threaded barrels, apply 12–15 ft-lbs torque using a calibrated wrench–overtightening distorts the action, while undertightening causes group dispersion.
The trigger group (#22–#30) demands meticulous cleaning after every 200 rounds. Use carbon-removing solvent specifically formulated for polymer-based lubricants–standard oils attract debris that binds sear engagement. Set trigger pull weight at 2.5–3.0 lbs for consistent performance; lighter settings increase accidental discharge risk.
Inspect the hammer pivot (#18) and its bearing surface (#19) monthly. Apply dry-film lubricant (e.g., Mil-Spec MIL-L-46010) to prevent galling; conventional grease attracts fouling. Replace the pivot pin if play exceeds 0.002 inches–this ensures uniform energy transfer to the firing pin.
When reassembling the frame components, align the barrel pivot (#4) before securing the forearm (#2). Misalignment here causes binding under recoil; verify by cycling the action with an unloaded chamber–smooth motion confirms proper fit. Use a torque screwdriver for mounting screws (#20); 8–10 in-lbs prevents loosening during firing.
Upgrade the ejector (#13) if extracting rimmed cartridges consistently fails. Factory ejectors may not fully clear brass under 500 fps velocities–aftermarket solutions (e.g., extended throw arms) improve reliability. Test extractor tension with a dial push gauge; ideal force ranges between 8–12 lbs for brass retention.
The stock assembly (#1) impacts zero retention. Check bedding surfaces for voids larger than 0.5mm; fills gaps with epoxy bedding compound if necessary. For synthetic stocks, avoid petroleum-based cleaners that degrade polymer integrity–wipe down with isopropyl alcohol instead.
Critical Torque Values
Follow these specifications to avoid mechanical failure:
– Barrel nut: 45–50 ft-lbs
– Scope mount base: 20–25 in-lbs
– Action screws: 18–22 in-lbs
– Grip screw: 12–15 in-lbs
Document each step with photographs before disassembly–this prevents misplacement of small springs (#21) or detents. For high-volume shooters, replace the firing pin spring (#16) every 1,500 rounds; fatigue weakens ignition consistency. Store components in antistatic trays to prevent corrosion; silica gel packets extend shelf life during long-term storage.
Locating Key Elements in a Single-Shot Pistol Mechanism
Start by examining the firing assembly–critical for operation. The hammer should move freely but with controlled resistance; listen for a crisp click at full cock. A weakened mainspring often causes misfires–test tension by pressing the spur manually. Replace if compression feels inconsistent.
- Barrel retention system: Check the pivot pin for wear. A loose fit causes misalignment; tighten or replace if movement exceeds 0.5mm.
- Action lock: Engage and disengage multiple times. Grinding or hesitation indicates debris buildup–clean with solvent, not compressed air.
- Trigger linkage: Measure pull weight (target: 3–4 lbs). Heavy creep suggests bent sear or contaminated engagement surfaces.
Inspect the fore-end assembly next. Cracks near stress points (visible under 10x magnification) require immediate replacement–aluminum fatigue is not repairable. Verify bedding surface flatness with a straightedge; deviations over 0.1mm affect shot consistency. Avoid aftermarket stocks with improper tang relief.
For optics mounting, confirm rail integrity–stripped threads or bent edges distort zero. Use torque specs (15–20 in-lbs) to prevent warping. If scope rings show signs of uneven tension (e.g., light leakage), lap them with 600-grit compound before reinstallation.
Step-by-Step Guide to Disassembling the Single-Shot Pistol Barrel Assembly
Ensure the firearm is unloaded and the hammer is in the down position before proceeding. Place the pistol on a stable, clean work surface with ample lighting. Use a punch tool or similar implement to depress the retaining pin located at the rear of the barrel housing, just above the frame. Apply steady pressure while gently wiggling the pin free–excessive force may deform it.
Slide the barrel forward approximately 0.25 inches (6.35 mm) to disengage it from the locking lugs embedded in the frame. If resistance occurs, check for debris or fouling buildup in the lug tracks; clean with a nylon brush if necessary. Once free, lift the barrel upward and away from the receiver while rotating it slightly counterclockwise to clear the extractor hook.
Inspect the barrel channel for residual carbon deposits or brass shavings–common after extended use. Use a bore guide or cleaning rod with a patch holder to swab the chamber and rifling surfaces. For stubborn fouling, apply a minimal amount of copper solvent sparingly, avoiding oversaturation which may damage bluing or finishes.
| Tool | Purpose | Torque Spec (if applicable) |
|---|---|---|
| Punch set (.125″ diameter) | Retaining pin removal | N/A |
| Nylon bore brush | Carbon/lead fouling removal | N/A |
| Torque wrench (inch-pounds) | Barrel nut reinstallation | 35-40 in-lbs |
| Non-marring plastic mallet | Seating components without marring | N/A |
Separate the barrel nut from the barrel by unscrewing it counterclockwise using a dedicated wrench or adjustable pliers protected with a cloth to prevent tool marks. If corrosion is present, soak the threads in penetrating oil for 10-15 minutes prior to attempting removal. Verify the muzzle threads are free of burrs; polish with a fine grit stone if irregularities are detected.
Reassemble by reversing the steps, ensuring the barrel’s breech face aligns flush with the frame’s locking surface. Apply a light coat of firearm-specific grease to the locking lugs and barrel nut threads. Tighten the nut to specified torque values–over-tightening risks frame stress fractures, while under-tightening may cause headspace variations.
Function test the pistol with dummy rounds before live fire. Check for smooth hammer operation and proper extraction/ejection cycle. If misalignment occurs, disassemble and re-inspect the barrel-to-frame fitment, focusing on the lug engagement surfaces.
Locating Original Equipment Manufacturer Components for Custom Single-Shot Action Bases
The primary source for factory-matched replacements is the official manufacturer’s website, where schematics and barcoded inventory lists are maintained under the “firearm accessories” section. Look for the serial-number lookup tool–it confirms compatibility with specific action generations (pre-1995 vs. post-2000) before checkout.
Koppelwerks in Texas stocks remaining NOS factory receiver blanks, trigger assemblies, and pivot pins, cross-referenced against original packaging lot numbers. Their catalog includes a search filter by action length (10″, 12″, 14″) and finish (blued, stainless, or Teflon coated).
Network of Specialized Gunsmiths
Angus Custom Firearms in New Hampshire maintains a waiting list for exact-match breech blocks and hammer struts, machining them in-house from bar stock when OEM inventory is exhausted. Precision tolerances are verified against original blueprint specifications provided by the legal successor entity.
Brownells carries select propulsion-mounted components under SKU #123-XXX-XXX, though quantities are limited to batches produced during the 2018–2020 remanufacturing run. Filter searches by “obsolete firearms” and sort by user-submitted compatibility ratings.
Secondary Market Channels
AmmoBunker’s user forums feature a classified thread dedicated to action frames, where verified sellers attach photographs of gauge readings (0.003″ feeler set) alongside firearm serial numbers. Escrow payments are held until third-party inspection confirms dimensional adherence.
eGunnery Auctions hosts quarterly liquidation sales of estate collections, where individual trigger shoes, sear springs, and barrel extension inserts are bundled by caliber group (rimfire, centerfire straight-wall, bottleneck). Review seller feedback scores–prioritize listings with high-resolution micrometer measurements.
Midway Firearms’ discontinued items portal occasionally restocks front and rear sight blades, extractor claws, and recoil plate kits. Sign up for inventory alerts; re-listing occurs within 24 hours of supplier warehouse updates.