What's New

A running log of meaningful updates to AR15.BUILD. We ship when something is genuinely useful, not on a schedule.

Compatibility checks: caliber & thread pitch

Latest · May 2026

Mismatched calibers are now flagged in your build — if your barrel, BCG, and magazine don't share a compatible caliber, the compatibility checker will catch it and explain why.
Multi-caliber magazines work correctly — a magazine that supports both 5.56 and .300 BLK will match either barrel without a false warning.
Thread pitch is now checked for muzzle devices and direct-thread suppressors — pairing a 1/2-28 barrel with a 5/8-24 muzzle device is flagged as incompatible. Missing thread data on either side surfaces as unknown rather than a false pass.
Components without a declared caliber or thread pitch are treated as open — the checker stays quiet until there is a genuine conflict with tagged data on the other side.
Suppressor bore-diameter compatibility (e.g. a .30 cal can hosting .223) will get its own dedicated check in a future update.

Chat personas, smarter context & nav update

May 2026

Bolt and Karen are live — pick your AI persona when you start a conversation. Bolt (B-017) is a plain-spoken field operator; Karen (K-4R3N) is a data-first analyst with dry wit and a habit of correcting bad premises. The persona is locked for the life of the conversation so context stays coherent.
The assistant now knows your gear — for logged-in users, the assistant pulls in your parts cabinet, active price alerts, and recent builds before it answers, so recommendations are grounded in what you actually own and what you are watching.
Community build search — ask for build examples or inspiration and the assistant will surface real public builds from the community alongside catalog results.
Stock status on product recommendations — when the assistant recommends a component, it now shows how many merchants currently have it in stock so you know whether it is actually available before you click through.
Chat is now in the nav — the chat icon in the top navigation and the footer link both go directly to the assistant, so it is one click away from anywhere on the site.

AI assistant, faster sign-in & chat plans

May 2026

The new AI assistant is live — use it for parts shopping, build questions, and general platform help in dedicated chat modes.
Sign in is easier — you can now create an account or log in with supported social providers instead of starting from scratch every time.
Chat plans are now available — Free, Premium, and Pro tiers now have a billing page where you can manage your subscription and upgrade when you need more usage.
Premium and Pro plans now keep helpful chat memory across sessions, and paid users can save a custom prompt to steer how the assistant responds.

Marketplace notifications improved

May 2026

Sellers can now notify the buyer when an item ships directly from the Mark as Sold flow on marketplace listings.
Gift listings now send clearer updates to both sides, including when a gift has been claimed and when it has been shipped.
The account area now includes a direct Notifications link so it is easier to keep up with marketplace activity.

Glock-compatible platform & AK improvements

April 2026

Glock-compatible builds are now supported — select the Glock-compatible platform in the builder and configure a Frame, Slide, Frame Parts Kit, and Slide Parts Kit as required build slots, just like an AR-15 lower build.
Glock-compatible components now have their own catalog pages — browse by type, filter by price and rating, and add parts directly to a Glock build.
AK build layout cleaned up — the AK builder now shows a dedicated Receiver slot and a cleaner Receiver & Action group, making the component structure easier to follow.

Popular Parts rankings

April 2026

See what builders actually choose — every component category now has a ranked list of the most-used parts, based entirely on what appears in real builds on AR15.Build. No sponsored ranking, no guesswork.
Rankings cover barrels, triggers, optics, handguards, BCGs, and dozens more — each with build counts, current pricing, and ratings where available.
Platform badges show whether a category applies to AR-15, AK, AR-10, or all platforms.
Find the full list at Popular Parts in the site footer, or browse straight to any category.

2A Places directory

April 2026

Public directory pages are live for state/city browsing and detailed location profiles across ranges, dealers, clubs, and training locations.
Submission flow is live so businesses can submit new locations directly from the directory, with Cloudflare Turnstile protection.
Account management view lets submitters review and edit their directory entries after submission.
New submissions are reviewed through admin approval workflows, and approved listings are geocoded as part of that process so map-ready coordinates are stored early.
The underlying data model now captures business types, services, facility features, and multiple lane types so the directory can support richer map and proximity features next.

Platform selector & catalog expansion

April 2026

Platform selector on the build page — switch between AR-15, AR-10, AR-9, and AK with a single click. The component list, build title, and page URL all update immediately.
The active platform is reflected in the URL (?platform=ak) — share or bookmark a pre-selected platform before saving a build.
Gear & Training section added to the parts catalog — Ammunition, Maintenance & Cleaning, and Training Devices now have dedicated browse pages.
Front sight and rear sight now have their own images in the catalog, making them easier to find when browsing.

Parts Cabinet & Shooting Logbook

April 2026

Parts Cabinet — track the components you own, not just what's in a build. Mark quantities, add notes, and see at a glance which parts are allocated to a build versus sitting as spares.
Cabinet entries are derived from your builds and any spare stock you add — no duplicate data entry.
Shooting Logbook — log range sessions with round counts, ammo, conditions, and notes. Link sessions to a specific build to track lifetime rounds fired per rifle.
Maintenance records — attach service entries to builds or components with round-count and date reminders. The logbook summary shows overdue and due-soon items at a glance.
Public sessions can be shared on your profile and build pages.

Merchant coupon codes

April 2026

Coupon offers now appear on supported merchant pages so you can quickly see active promo codes, offer summaries, and merchant landing links in one place.
Eligible product pages now show a compact coupon hint directly in the retailer list, so you can spot savings without hunting through a separate promo page.
This gives participating merchants another way to surface affiliate offers directly to users who are already comparing prices and deciding where to buy.

Color filtering & catalog data

April 2026

Filter by color — product list pages now support filtering by color, so you can quickly narrow down components to match your build's finish or aesthetic.
Color is now a first-class catalog attribute — components carry a standardized color value extracted and maintained as part of the AI enrichment pipeline.

Notifications & account activity

March 2026

In-app notifications — account activity now has a dedicated notifications center, including unread counts and mark-as-read controls.
Browser push support — you can enable browser notifications from your account settings for supported notification types.
Notifications now cover meaningful events across marketplace activity, comments, and other account actions.

Brand & merchant browsing improvements

March 2026

Featured merchants now appear at the top of the merchant directory, followed by the rest of the list alphabetically.
Brand and merchant pages now support richer public profiles, including logos and editorial descriptions.
The main site navigation now makes it easier to browse by categories, brands, or merchants without going back to the homepage.

Optic mount categories & catalog expansion

March 2026

Scope Mounts & Rings — scope rings, one-piece mounts, and cantilever mounts now have their own dedicated category and build slot.
Red Dot Mounts & Risers — risers, offset mounts, piggyback mounts, and footprint-specific micro-dot mounts are now browsable separately from scope hardware.
Magnifier Mounts — flip-to-side and flip-to-center magnifier mounts are now a first-class build slot, so you can pair a magnifier mount alongside a red dot mount and scope mount in the same build without conflicts.
The builder supports all three new mount slots independently — you can now configure an LPVO + cantilever mount + offset red dot + flip magnifier mount in a single build.

Retailer pages, platform expansion & more

March 2026

Retailer pages — each retailer in the catalog now has a dedicated page listing the components they carry, with links to current pricing.
AK & AR-9 platform support — AK and AR-9 components are now properly classified and selectable alongside AR-15 and AR-10.
Regulated badge — lower receivers and suppressors in your build now display a red Regulated badge as a reminder that these components are subject to federal regulations.
Expanded correction submissions — you can now suggest corrections for a component's material, caliber, type, and compatible platforms, not just its name or price.

Build tool improvements

March 2026

Bundle item override — got a complete lower but want a different trigger? You can now replace any individual item included in a bundle with a component of your choice. The build reflects both the bundle and your override.
Each selected component in your build now has a direct link to its product page, so you can pull up specs, pricing, and reviews without leaving your build.

Sort by popularity and rating

Product list pages now support sorting by popularity — ranked by how many public builds include each component — and by rating.
Sort order (ascending or descending) can be toggled independently of the sort field.

Richer compatibility data

We're expanding the dimensional data we capture across component types. This data isn't yet wired into the compatibility checker, but it lays the groundwork for more precise fitment checks in the future.

Gas blocks now capture bore diameter — the critical spec for matching to your barrel's journal diameter.
Scopes and magnifiers now capture tube diameter (1", 30mm, 34mm, 35mm) and optic mounts capture their ring bore diameter.
Barrel gas block journal diameter is now explicitly extracted rather than inferred, completing the barrel → gas block data chain.
Buffer tubes and stocks/braces now capture their respective outer and inner diameters, covering mil-spec vs commercial fitment.

Mobile browsing improvements

Product list pages now show a clean card layout on phones — no more horizontal scrolling through a wide table.
Build hero images and pagination fixed across all public build pages.

Price alerts

Set a target price on any component and get notified when it drops below your threshold.
Alerts are managed from your account and work across all tracked component types.

Inventory tracking

Components now track in-stock and out-of-stock status based on merchant data, so you can see at a glance what's available.

Brand pages & global search

Every manufacturer now has a dedicated page listing all of their components in the catalog.
Global search now returns products, brands, builds, and guides from a single search bar.
Improved SEO and internal linking across product and brand pages.

Improved product filtering

Product list pages now support filtering by material, caliber, barrel length, and rating.
Sort by name, price, or manufacturer — in either direction.
Active filters are preserved in the URL so you can share or bookmark a filtered view.
Pagination added to product lists to handle large catalogs efficiently.

Guides & articles

A new guides section covers build planning fundamentals, left-handed AR-15 considerations, and more.
Guides are linked from relevant product and tool pages to surface them in context.

Planning tools

Muzzle velocity estimator — estimate velocity based on barrel length and caliber.
Sound level estimator — understand how suppressor choice affects decibel output.
Gas & buffer pairing — guidance on matching your gas system length to buffer weight.
Zero & holdover calculator — work out point-of-impact at various distances given your zero and optic height.

Expanded component catalog

Added suppressors as a browsable and build-selectable component type.
Optics split into three distinct categories: scopes, red dots, and magnifiers — each with their own dedicated product pages.
Several additional component types added across the catalog.
AI-assisted duplicate detection runs continuously in the background. Confirmed duplicates are auto-merged to keep the catalog clean and accurate.

Marketplace

Sellers can now mark listings as sold once a deal is complete.
Expanded search filters let buyers narrow by condition, price range, and location.
Gift system lets community members send parts as gifts to other builders.
Marketplace listings are now indexed for search engine discoverability.