Straight answers to the questions that actually decide a build — no filler, no affiliate links, and nothing for sale.

AR Build Guides

Every guide here is written to answer one real question a builder asks before spending money. The numbers come from the same engines behind the build planner.

Bullet Weight Explained: What Grain to Shoot, and WhyGrain is the single spec people obsess over and understand least. Here's what it actually changes — and how to pick without overthinking it.Best AR Caliber for Home DefenseIndoors, the priorities invert. Range and energy matter less than control, over-penetration, and what a muzzle blast does to your hearing in a hallway.Best AR Caliber for Hunting, by Game SizeMatch the cartridge to the animal and to your state's rules — those two constraints eliminate most of the list before preference ever enters into it.Best AR Caliber for Long-Range ShootingLong range is a wind problem, not an energy problem. The cartridge that drifts least under a misread wind call is the one that wins.The Quietest AR Calibers for Suppressed ShootingA suppressor only silences the muzzle blast. If the bullet is supersonic, it still cracks — and that crack is the loudest thing left.Your First AR-15 Build: What Actually MattersMost first-build mistakes aren't about picking a bad part — they're about picking two good parts that don't work together.AR Barrel Length: Velocity, Sound, and the Legal LineEvery inch of barrel is a trade between velocity and handling — and below 16 inches, a legal question enters the picture.

Looking for a specific caliber?

The caliber guide covers every cartridge the AR-15, AR-10, and AR-9 platforms run — with computed velocity, energy, and suppressed-sound estimates for each.

ArmoryBench is a free build-planning tool — not a store. We don't sell, ship, broker, or transfer firearms, parts, or accessories, and we're not affiliated with, endorsed by, or sponsored by any manufacturer or retailer. It's just a sandbox to play with hypothetical builds and plan your next one. All product names, brands, logos, and trademarks are the property of their respective owners; we claim no ownership and use them only to identify parts.

Legal & safety disclaimers (read me)

Just a Planning Tool — Not a Store

ArmoryBench is a free, informational planning and visualization sandbox. You use it to experiment with hypothetical AR-15/AR-10 configurations — nothing more. There is no cart, no checkout, no inventory, and no way to buy anything here. We do not sell, offer for sale, ship, transfer, broker, or facilitate the sale of any firearm, receiver/frame, part, accessory, or NFA item. Any purchase must be made separately through the actual manufacturer or a licensed dealer.

Trademarks, Brands & No Affiliation

All manufacturer names, product names, model names, brands, logos, and trademarks are the property of their respective owners. ArmoryBench is not affiliated with, authorized by, endorsed by, or sponsored by any manufacturer, brand, or retailer mentioned. Names and specs are used purely to identify and describe parts so you can plan a build (nominative reference). We make no claim of ownership to any third-party mark, and no endorsement or partnership is implied.

No Warranty — Verify Everything

Part specs, weights, prices, compatibility results, reviews, and availability are best-effort estimates and community-sourced information that may be incomplete, outdated, or wrong. They are provided "as is," without warranty of any kind. This is not legal, engineering, gunsmithing, or safety advice. Independently verify all specs, compatibility, and current law with the manufacturer and a qualified professional before buying, assembling, or firing anything. You are solely responsible for how you use this information.

Pricing

All prices shown are approximate MSRP (manufacturer suggested retail) for reference only — ArmoryBench does not sell parts. Street prices are often lower, so always check current pricing and shop around; you can frequently find sales and better deals from reputable retailers.

Sound Is Ranked, Not Measured

ArmoryBench does not publish decibel levels. A 2026 review of published suppressor data found that most manufacturers release either nothing at all or bare numbers without the test standard, weighting, and microphone position needed to compare one against another — and that most cartridges have no published unsuppressed reference level whatsoever. Rather than present figures assembled from sources like that, we show a relative ranking: how loud one configuration is likely to be next to another, and how much to trust that comparison.

These rankings are algorithmic approximations for educational purposes only. They are not laboratory measurements and are no substitute for professional acoustic testing or OSHA/NIOSH occupational noise guidance. Peer-reviewed testing has found no suppressed centerfire rifle configuration reliably below the hearing damage threshold at the shooter’s ear. Always use proper hearing protection when firing any firearm, suppressed or not.

Ballistic Coefficients

Where a manufacturer publishes a ballistic coefficient we use it. Most hunting, defensive, and house-brand loads don't publish one, so those use a value typical of the bullet's construction, flagged as an estimate wherever it appears. Be aware that advertised BCs often run optimistic — some bullets measure meaningfully lower in the field than on the box, and the gap widens past roughly 600 yards as the bullet slows. Treat every trajectory here as a starting point for confirming on paper, not a substitute for it.

Exterior Ballistics

Trajectory, drop, wind drift, and energy figures are computed estimates based on a standard point-mass ballistic model and the inputs you supply. Actual performance varies with atmospheric conditions, chronograph accuracy, and firearm/ammunition variance. Verify zero and trajectory data at the range before hunting or competition use.

Reloading Data

This tool does not calculate chamber pressure and never generates a charge weight from first principles. Any future custom-load feature is constrained to interpolation between published load-data points and must never be the sole basis for a handload. Always verify any load against current published data from the powder and bullet manufacturer, start at the published starting load, and never exceed a published maximum charge.

Not a Firearms Dealer

This app does not sell, ship, or transfer firearms, receivers/frames, or NFA-regulated items. It is a research and planning tool only. All purchases of receivers, frames, or complete firearms must be completed through a licensed Federal Firearms Licensee (FFL).

NFA Items

Configurations involving suppressors, or a barrel under 16" paired with a shoulder stock (SBR), require ATF approval (Form 1 or Form 4), a background check, and an approval wait period before assembly or possession. As of January 1, 2026, the associated $200 federal tax was eliminated by federal law; the registration, background-check, and approval process itself was not eliminated and remains fully in effect. Verify current law in your jurisdiction — you are solely responsible for completing all required legal steps.

Your Responsibility

Building or modifying a firearm carries legal and safety obligations that vary by federal, state, and local law. You alone are responsible for ensuring any configuration you build is legal where you live and is assembled safely. To the fullest extent permitted by law, ArmoryBench and its authors disclaim all liability for any decision, purchase, assembly, or outcome arising from use of this tool.