Build Your Own Custom AR15 With an 80 Percent Lower

The AR-15 80 percent lower is your starting point for a truly custom build, offering a blank canvas that’s not legally considered a firearm until you finish it. This unfinished component lets you skip the background check and serial number, giving you complete control over your project from the ground up. Whether you’re a DIY enthusiast or a precision shooter, it’s the most hands-on way to own a rifle built exactly how you want it.

Understanding the 80% Receiver: The Basics

An 80% receiver is an unfinished firearm component, typically a lower receiver for rifles or pistols, that has not been machined to a functional state. It lacks critical features like the fire control cavity, requiring the buyer to complete the drilling and milling process themselves. This distinction means the unshaped block is legally not considered a firearm by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), allowing it to be sold without a serial number or a background check. The receiver’s incomplete nature is the cornerstone of its legality; however, once the final machining is performed, the builder creates a functional firearm that may be subject to local regulations. Understanding this legal boundary is crucial for any DIY enthusiast, as the resulting homemade weapon must comply with state and federal laws regarding serialization and ownership. The process demands careful attention to technical specifications and material hardness.

What Defines an Unfinished Lower Receiver

An 80% receiver is a firearm component that is not yet legally considered a firearm, as it is incomplete and non-functional. To finish it into a working lower receiver, the user must perform essential machining operations, such as drilling the trigger pin and safety selector holes. This process allows individuals to legally manufacture their own firearm for personal use, without a serial number or federal background check, provided it complies with state and local laws. Understanding this distinction is critical for anyone exploring DIY gun building, as it sits in a unique legal gray area where federal regulations apply only after the receiver is fully completed and functional.

Q: Is an 80% receiver legal to own without a background check?
A: Yes, at the federal level, you can purchase and own an 80% receiver without a background check because it is not classified as a firearm. However, some states and cities have their own restrictions, so you must verify local laws before buying or machining one.

Key Differences Between a Finished and Unfinished Frame

An 80% receiver is a firearm component that has not been fully machined or completed, meaning it is not legally classified as a firearm under federal law. 80 percent receivers require final milling or drilling to become functional. This incomplete status allows individuals to build their own firearms without serial numbers or background checks, as long as they do not sell the finished product. The receiver—typically the lower receiver for AR-15 style rifles—houses critical parts like the trigger and magazine. Builders must finish the fire control pocket, trigger pin holes, and safety selector channels using jigs and tools. Compliance with local laws is essential, as some states regulate these blanks as firearms. Common considerations include:

• Material choice: aluminum (modeled on legacy mil-spec designs) or polymer (lighter, easier to machine).
• Jig type: multi-platform modular jigs (for various calibers) or single-use jigs (specific to one receiver brand).
• Post-completion requirements: engraving a serial number if building for personal use with intent to transfer.

Finishing an 80% receiver requires precise drilling and patience to avoid damaging the part. Understanding ATF rulings on receiver classification is critical to staying within legal boundaries.

Why Enthusiasts Choose the DIY Route

The 80% receiver, often called an “80% lower,” is the foundation for a firearm that you, the builder, complete at home. It’s a partially machined block of aluminum or polymer, lacking critical fire-control areas like the trigger pocket and safety selector hole. This is the key distinction: it’s not yet a firearm under federal law, allowing direct purchase without a background check. Your role is to finish the remaining 20% using a jig and drill. That single act of drilling the final hole transforms inert metal into a functional receiver, and with it comes the responsibility of understanding state laws and serialization requirements.

80% lower receivers are legal to own, but the moment you complete one, you’ve created a firearm.

• Step One: Select a receiver material (e.g., aluminum 7075-T6 for durability) and a compatible jig kit.
• Step Two: Carefully drill the trigger pocket, hammer pin holes, and safety selector using a drill press or hand router.
• Step Three: Double-check dimensions against a technical drawing to ensure safety and function.

Q&A:
Q: Can I sell a completed 80% receiver?
A: Only if you are a licensed manufacturer. Private sale of a completed, unserialized receiver is illegal in many states. Always check local regulations.

Legal Landscape and Compliance Considerations

The hum of the server room was a constant reminder that for a fledgling tech startup, innovation moved at the speed of light, but the law moved at the speed of ink. Our founder, a visionary architect of code, had initially dismissed compliance as a dull afterthought. That was until a midnight email from a regulatory body landed in his inbox, freezing our entire digital asset rollout. We quickly learned that a single overlooked data residency requirement could shatter a company’s future. Navigating this legal labyrinth became our new reality, where every privacy policy revision felt like a chess move against liability.

The most brilliant product is just a liability without a robust compliance framework.

We now treat regulations as a living map, not a static rulebook, understanding that data privacy law is the bedrock upon which customer trust is built. For any enterprise, mastering these evolving legal landscapes isn’t just about avoiding fines; it is a strategic advantage that defines industry leadership in an age of hyper-scrutiny.

Federal Regulations Governing Partially Machined Receivers

Navigating the legal landscape for digital products or business operations means staying on top of data protection laws like GDPR, CCPA, or the newly emerging AI regulations. You need a clear privacy policy and terms of service, and if you handle user data, compliance audits are non-negotiable to avoid hefty fines. Data privacy compliance now directly impacts customer trust and your bottom line. Key areas to keep an eye on include: Consumer rights (access, deletion, portability requests), cookie consent (ensuring opt-in mechanisms are clear), and cross-border data transfers (like the EU-US Data Privacy Framework). Don’t just set it and forget it; laws evolve fast, so regular reviews are a smart habit to protect your venture.

State-by-State Restrictions You Need to Know

Navigating the legal landscape today means understanding that compliance isn’t just a boring checklist—it’s your business’s shield. Data privacy regulations like GDPR and CCPA now set the global standard, demanding transparent data handling or risking massive fines. Beyond privacy, you must watch for evolving consumer protection laws and industry-specific rules, from healthcare (HIPAA) to finance (SOX). Non-compliance can lead to lawsuits, reputational damage, and lost customer trust.

• Key areas to monitor: Data privacy, employment law, and anti-corruption rules.
• Common mistake: Ignoring cross-border regulations if you operate in multiple countries.
• Quick tip: Hire a legal advisor early—it’s cheaper than a fine.

Q: Does compliance only apply to big corporations?
A: No—small businesses face serious penalties for ignoring, say, GDPR or tax laws. Start with basics like a privacy policy and clear terms of service.

Serialization Requirements and Transfer Rules

The legal landscape for digital operations requires strict adherence to data protection regulations like GDPR and CCPA, which mandate transparent data handling and user consent. Non-compliance can result in substantial fines and reputational damage. Regulatory compliance frameworks also cover e-commerce laws, cybersecurity standards such as NIST, and sector-specific rules in finance or healthcare. Organizations must conduct regular audits to assess risks and update policies as legislation evolves. Additionally, cross-border data transfers face increasing scrutiny, necessitating legal safeguards like Standard Contractual Clauses. Staying informed on emerging laws around AI and digital services is essential for minimizing liability and ensuring operational continuity.

Materials and Manufacturing Choices

The selection of materials and manufacturing processes is a critical determinant of a product’s lifecycle cost, performance, and environmental footprint. Engineers must balance factors like tensile strength, thermal resistance, and weight against the scalability and energy demands of production methods such as injection molding, additive manufacturing, or die casting. For instance, a switch from machined aluminum to a composite polymer can reduce weight and part count, yet may require a significant investment in new tooling. Conversely, utilizing advanced robotics for welding can improve precision but increases upfront capital expenditure. Ultimately, every choice involves a trade-off between raw material availability, waste generation, and the operational constraints of the factory floor. This holistic evaluation, known as Design for Manufacturing (DFM), ensures that the final product is both economical to produce and durable in service. Adhering to these principles optimizes manufacturing efficiency without compromising structural integrity.

Aluminum vs. Polymer: Strengths and Trade-Offs

Selecting materials and manufacturing processes is a critical decision that directly impacts product performance, cost, and sustainability. Early material selection is essential for design for manufacturing success, as it dictates everything from tooling choices to assembly methods. Common material categories include metals, polymers, ceramics, and composites, each offering distinct properties like strength, weight, or thermal resistance. Manufacturing methods range from subtractive processes like CNC machining to additive techniques such as 3D printing, with injection molding and casting suited for high-volume production. Always prototype with the intended production material to avoid costly late-stage redesigns. Key considerations include:

• Part geometry and complexity
• Required production volume
• Environmental and regulatory constraints
• Cost per unit vs. tooling investment

Billet vs. Forged Construction for Home Builders

Strategic material selection dictates manufacturing feasibility and product lifespan. For high-stress components, engineers prioritize alloys over polymers, balancing tensile strength against weight. The manufacturing process must then align with the material’s properties: sustainable manufacturing practices reduce waste by choosing near-net-shape methods like precision casting over subtractive machining. Production volume further refines the choice, with injection molding favored for high-throughput plastics, while CNC milling suits low-volume, high-tolerance metal parts. Surface treatments, from anodizing to powder coating, are specified based on the intended operating environment, preventing corrosion without compromising the substrate’s integrity. This closed-loop decision process ensures cost efficiency and product durability.

Cerakote, Anodizing, and Other Finishing Options

Selecting materials and manufacturing processes is a critical decision that directly impacts product cost, durability, and sustainability. Sustainable material sourcing requires balancing performance with environmental impact, often favoring recycled composites or bio-based polymers. For production scalability, consider these core factors:

• Material properties: tensile strength, thermal resistance, and weight constraints.
• Process compatibility: injection molding for high-volume plastic parts versus CNC machining for precision metal components.
• Cost efficiency: trade-offs between upfront tooling expense and per-unit manufacturing time.

Prototyping with additive manufacturing allows rapid validation before committing to hard tooling. Prioritize design for manufacturability (DFM) to minimize waste and rework. A thorough lifecycle analysis ensures your chosen path supports both functional requirements and corporate sustainability goals.

Essential Tooling for Finishing a Receiver

To achieve a flawless receiver finish, you must invest in precision files, a quality vise with soft jaws, and a set of receiver-specific jigs. Start with coarse files for rapid material removal, then switch to fine-cut files and 400-grit sandpaper for a glass-smooth surface. A rigid receiver block prevents marring and ensures straight lines. For anodized aluminum, use a sharp carbide deburring tool to clean holes and edges without tearing.

Neglecting proper jigs will ruin your receiver’s tolerances—precision tooling is non-negotiable for a functional, professional build.

Finally, finish with abrasive pads and a protective oil coat; this prevents oxidation and highlights the metal’s natural luster, giving you a durable, show-quality component.

Jig Systems and Fixtures for Precision Milling

Finishing a receiver demands precision tooling to ensure flawless operation and durability. The most critical equipment includes a drill press for perfectly perpendicular hole alignment, a torque wrench for spec-fastening components, and a set of quality jigs to maintain receiver geometry during work. High-quality receiver finishing tools eliminate costly mistakes and guarantee proper function. A complete bench setup should feature:

• End mills (4mm and 6mm) for trigger pocket and safety selector cuts
• Reamers for chamfering and deburring sharp edges
• Calipers for exact measurement against blueprint specs
• Thread taps for cleaning barrel and buffer tube threads

Investing in these tools from reputable manufacturers transforms a rough forging into a reliable, mil-spec component. Without them, even skilled builders risk ruining an expensive receiver.

Drill Press vs. Router vs. Manual Hand Tools

Finishing an AR-15 receiver requires specialized tooling to achieve a professional, mil-spec fit and reliable function. Precision jigs and fixtures for receiver finishing are non-negotiable; they guide your work on critical areas like the trigger pocket, bolt catch channel, and fire control group shelf. Without a hardened steel jig, misalignment is almost certain. Essential tools include a drill press or plunge router for depth control, a set of end mills and router bits designed for 7075-T6 aluminum, and a deburring tool to clean every sharp edge. A set of good-quality transfer punches helps mark hole locations, while a torque wrench is vital for correctly installing the barrel nut and buffer tube castle nut. Invest in these items first, as cheap alternatives often lead to scrapped lowers.

Must-Have Bits, End Mills, and Safety Gear

Essential tooling for finishing a receiver centers on precision, safety, and proper material removal. Start with a quality 80% jig and drill press to accurately locate and bore the trigger pin and hammer pin holes. A set of hardened steel end mills and reamers is critical for cleaning the fire control cavity without damaging the material. Use a deburring tool on all sharp edges, then finish with 220- and 400-grit sandpaper, focusing on the rail slots and pocket walls. Always check headspace with proper gauges before final assembly.

Never force the fire control group into a receiver that hasn’t been properly deburred—tight spots indicate incomplete machining.

For the final touch, apply a corrosion-resistant coating like Cerakote or a baked-on gun finish after complete degreasing. A final function check with snap caps verifies trigger reset and sear engagement. Consider including a small arbor press for pin installation and a torque wrench for buffer tube attachment.

Step-by-Step Completion Process

The step-by-step completion process begins with a clear goal, breaking every complex task into manageable, sequential actions. Each phase builds logically on the last, eliminating guesswork and reducing friction. You start by outlining core requirements, then prioritize urgent subtasks, creating a dynamic workflow that maintains momentum. As you tick off each step, progress becomes visible, fueling motivation. Regular checkpoints ensure nothing slips through the cracks, while adaptive adjustments keep you agile. This structured yet flexible approach transforms overwhelming projects into a series of swift, satisfying wins. By following this precise pathway, you unlock efficiency, minimize errors, and drive consistent, measurable results—turning ambition into achievement with pace and precision.

Preparing Your Workspace and Securing the Blank

The old wooden compass sat beside the blueprint, its point still marking the center of the circle. The step-by-step completion process started not with a flurry of action, but with a single, clear intention. First, I gathered the forgotten tools and materials from the dusty shelves. Next, I laid out the cuts for the oak frame, measuring twice for every single saw stroke. Then came the assembly, a quiet ritual of clamping and joining, where each piece clicked into place like a memory resurfacing. Mastering the step-by-step completion process turns a chaotic pile of parts into a finished, functional story. Finally, I sanded the sharp edges smooth and applied a coat of oil, watching the grain glow. The process was never about speed, but about honoring each small victory along the way.

Locating and Drilling the Trigger Pocket

The Step-by-Step Completion Process transforms complex projects into manageable victories. Begin by clearly defining your end goal to establish direction. Structured task sequencing ensures efficiency, so break the main objective into smaller, logical actions. Next, prioritize these steps based on dependency and impact, tackling high-value items first to build momentum. Execute each task deliberately, pausing to verify quality before proceeding. Finally, review the completed sequence for any missed details or optimization opportunities. This method eliminates overwhelm and provides a clear roadmap from start to finish, turning abstract ambitions into tangible results with consistent, incremental progress.

Cutting the Fire Control Group Recess

A successful step-by-step completion process transforms overwhelming tasks into manageable, measurable actions. Begin by breaking the goal into clear stages, each with a defined endpoint. Next, prioritize these steps—tackle the hardest or most critical segment first to build momentum. After that, execute each phase sequentially, checking off completed items to visualize progress. Finally, review the entire sequence for errors and confirm alignment with the original objective. This rhythm of action and review keeps projects moving without stalling on perfection.

Finishing the Safety Selector and Hammer Pin Holes

The Step-by-Step Completion Process breaks complex tasks into manageable phases, ensuring consistent progress and quality control. Begin by defining the project scope and deliverables to establish clear boundaries. Next, break the work into sequential stages, each with specific milestones and deadlines. Task dependency mapping is critical here, as it identifies which steps must precede others. Execute each step in order, verifying completion against predefined criteria before moving forward. Finally, conduct a review phase to confirm all objectives are met and document any issues for future reference. This method reduces errors and supports tracking of overall project advancement.

Troubleshooting Common Completion Mistakes

When Tom first deployed his chatbot, users complained it “forgot” their names mid-conversation. He realized the model wasn’t broken; the prompt lacked a crucial system instruction to repeat key context. By adding a simple reminder, responses became coherent. This is the heart of troubleshooting common completion mistakes—often, the issue isn’t the AI’s intelligence, but how we frame the request. Another day, Sarah noticed her writing assistant kept inventing facts. The fix wasn’t punishing the model, but adjusting the temperature setting to lower randomness. Like tuning a radio, a small turn reduces static. Whether it’s a forgotten persona or hallucinated data, each problem whispers back: check your foundation before blaming the machine.

Avoiding Off-Center Pocket Cuts

When troubleshooting common completion mistakes in large language models, the core issue often lies in ambiguous or under-specified prompts. Effective prompt engineering is your first line of defense. For instance, a vague request like “Write a story” yields generic output, while “Write a 100-word sci-fi story about a rogue AI on Mars, using a first-person narrative” provides clear guardrails. Typical errors include the model generating irrelevant details or stopping mid-thought. To fix these:

• Clarify context: Add background, tone, or audience specifics to narrow the output.
• Set length and structure: Explicitly state word count or format (e.g., “list three reasons”).
• Iterate with examples: Provide a sample completion to guide style and focus.

By systematically refining your instructions, you transform erratic completions into precise, actionable content that aligns with your goal.

Fixing Burred Edges and Rough Tolerances

Effective troubleshooting of common completion mistakes begins with identifying output that fails the original task specification. A critical SEO-relevant phrase to integrate is prompt engineering refinement. Common errors include verbosity, irrelevant tangents, and factual inaccuracies. To address these, apply the following structured checks:

• Verbosity: Add explicit length constraints like “in 3 sentences” or a word limit.
• Irrelevance: Rephrase the core instruction to be more directive, e.g., “List only the key steps.”
• Inaccuracies: Specify a trusted source or request verifiable citations, then cross-check outputs manually.

Finally, analyze the model’s pattern: repeated errors often indicate ambiguous cues in the initial prompt. Adjusting granularity—from broad goals to single, concrete actions—directly reduces completion drift and enhances output reliability.

Addressing Incomplete or Shallow Milling Passes

When troubleshooting common completion mistakes in language models, focus first on prompt engineering fundamentals. Vague instructions often yield irrelevant or repetitive outputs. To improve precision, verify that your prompt includes clear constraints like format, length, and tone. Critical errors include:

• Missing context: Models default to generic responses without framing.
• Overloaded requests: Asking for too many tasks in one prompt dilutes accuracy.
• Negative phrasing: Commands like “don’t mention X” can backfire; instead, redirect positively.

For completion quality, adjust temperature (lower for deterministic answers, higher for creativity) and max tokens to avoid truncation. Always test outputs by isolating variables—change one prompt element at a time. If repetition occurs, increase frequency penalty. These tactics transform raw outputs into reliable, context-aware results.

Assembly and Parts Compatibility

In the modern build ecosystem, assembly and parts compatibility is the single non-negotiable factor separating a flawless rig from a costly paperweight. Every component must communicate perfectly, ensuring that a motherboard’s socket aligns with the CPU, the RAM voltage matches the supported standard, and the power supply provides adequate wattage for the entire system. Ignoring these critical pairings invites thermal throttling, electrical failure, or physical incompatibility. You cannot afford guesswork; precise selection guarantees seamless installation, optimal performance, and long-term reliability. Whether upgrading a single drive or constructing a new workstation, confirm every dimension, connector, and chipset configuration. This rigorous attention to detail transforms assembly from a gamble into a confident, repeatable success, delivering a machine that runs exactly as engineered.

Selecting a Quality Lower Parts Kit

Assembly and parts compatibility ensures that mechanical components fit and function together without modification. This involves verifying critical specifications such as dimensions, mounting patterns, electrical ratings, and material tolerances. For example, a processor must match its socket type, a brake caliper must align with its rotor diameter, and a power supply must deliver correct voltages. Common compatibility checks include:

• Physical size and clearance within the chassis
• Interface standards (USB, PCIe, SATA)
• Voltage and current requirements
• Firmware or driver support

Ignoring compatibility leads to assembly failure, performance loss, or damage. Always consult manufacturer datasheets and cross-reference part numbers before assembly. Proper planning reduces rework and ensures a reliable final product.

Matching Triggers, Grips, and Stocks to Your Build

Assembly and parts compatibility determines whether a build functions seamlessly or becomes a frustrating puzzle of misfits. Every component—from motherboard sockets to RAM speeds and cooler clearance—must align with precise specifications. Ensuring PC component compatibility prevents costly returns and performance bottlenecks. For example, an Intel LGA1700 CPU demands a matching chipset, while a GPU’s length must fit the case without blocking front fans. Even subtle mismatches, like an outdated BIOS or insufficient power supply wattage, can halt assembly. To avoid headaches, cross-reference these key elements:

• CPU & Motherboard: Socket type (e.g., AM5 vs. LGA1700) and chipset support
• RAM: DDR generation (4 vs. 5) and motherboard slot configuration
• Cooling: Heatsink height vs. case width and fan mount positions
• PSU: Wattage headroom and required GPU power connectors

Treat compatibility checks like a pre-flight checklist—skip one, and P80 your build might never leave the ground.

Checking Fitment with Upper Receivers

Assembly and parts compatibility is the non-negotiable foundation of any successful build. Every component—from the motherboard socket to the RAM module’s pin layout—must precisely align to ensure flawless operation. A mismatched CPU or incompatible connector can render an entire system non-functional, wasting time and budget. Always verify your physical dimensions (e.g., GPU length, cooler height) and electrical standards (e.g., PCIe generation, PSU wattage). Key checks include:

• Socket type (LGA1700 vs. AM5) and chipset generation.
• RAM: DDR version, voltage, and motherboard slot configuration.
• PSU: Form factor (ATX, SFX) and required power connectors.
• Cooler: Clearance for RAM slots and case width.

Prioritizing these criteria guarantees a seamless, stable build without costly returns or repairs. Do not guess—use official compatibility tools and spec sheets every time.

Maintenance and Upkeep for Home-Built Firearms

Proper maintenance and upkeep for home-built firearms is non-negotiable for reliability and safety. Unlike factory models, your creation has unique tolerances and metal finishes that demand consistent attention. After each range session, thoroughly clean the bore and action using a high-quality solvent and lubricant, paying special focus to hand-fitted parts to prevent galling. Inspect for wear on critical zones like the bolt face, extractor, and sear surfaces every 500 rounds. Regular inspection will catch subtle cracks or erosion before they cause a catastrophic failure. Store your firearm in a climate-controlled safe with desiccant; moisture is the enemy of amateur-machined steel.

Q: Can I use standard firearm lubricants on my home build?
A: Yes, but avoid over-application. Home-built parts often lack the polished surfaces of commercial guns, so excess oil attracts carbon and grit, accelerating wear. A thin, high-temp grease on rails and lugs outperforms liquid oil.

Lubrication Points Specific to Completed Receivers

Proper maintenance for home-built firearms is not optional; it is a core responsibility that ensures both safety and longevity. Because these components often lack the factory-level finishing of commercial models, raw metal contact points are more prone to galling and corrosion. Regular lubrication and preservation of self-built firearms prevents premature wear on hand-fitted parts. A consistent cleaning routine should immediately follow every range session to remove carbon fouling and moisture. Key areas to inspect include:

• Bolt face and firing pin channel for debris.
• Trigger group sear surfaces for burr formation.
• Barrel crown for accidental nicks during assembly.

“A neglected polymer lower may flex, but a neglected metal component will fail—check tolerances before every use.”

Finally, store the firearm in a dehumidified environment with a light oil film on all steel surfaces to defeat rust, particularly if the frame is 80% billet or amateur-welded steel.

Inspecting for Wear After Use

Regular inspection of home-built firearm components is non-negotiable for safety and longevity. After each use, disassemble the frame, slide, and barrel to remove carbon fouling and debris using a solvent-soaked patch. Apply a light coat of high-quality gun oil to all metal contact points, avoiding over-lubrication that attracts grit. For polymer or 3D-printed frames, inspect for stress cracks or layer separation under bright light. Replace worn springs and firing pins according to manufacturer recommendations or after every 500–1,000 rounds. Store the weapon in a dehumidified safe to prevent rust on unfinished steel surfaces. Never skip function-checking the trigger reset and safety mechanisms after cleaning. A well-maintained build performs reliably, while neglect risks catastrophic failure.

Storage Tips to Preserve the Machined Surface

Home-built firearm maintenance demands rigorous, corrosion-preventative routines. Unlike factory models, these builds lack commercial quality control, making regular inspection of headspace, trigger engagement, and bolt-face integrity critical for safety. Always clean and lightly oil all contact surfaces after each use, paying special attention to proprietary parts where galling is common. For solvent choice, use only non-abrasive formulas to protect hand-finished components. A chronic failure to lubricate sear surfaces significantly increases the risk of unintended discharge.

1. Inspect: Check all pins and screws for backing out after every 100 rounds.
2. Lubricate: Apply a thin film of synthetic grease to the slide rails and bolt lugs; avoid pooling around the firing pin channel.
3. Document: Log each shooting session in a notebook, noting any unusual wear patterns or extraction issues.

Q&A:
Q: How often should I replace recoil springs on a homemade pistol?
A: Every 1,500 to 2,000 rounds, as hand-finished springs fatigue faster than factory-tested units. Premature replacement is cheaper than frame damage.