CMT FAQs.

Only for a lower. A stripped lower receiver is a firearm under federal law, so it ships to the licensed dealer (FFL) you enter at checkout, never to your door. We confirm the licence with the dealer before the package leaves, and you complete the ATF Form 4473 and the background check with the dealer in person. A stripped upper receiver is not a firearm and ships direct to you.

You must be 18 or older to use the site and 21 or older to purchase a serialized receiver. Federal and state eligibility rules still apply at the dealer, so check both before you order: a receiver that cannot lawfully be transferred to you cannot be returned for a refund of the transfer fee.

7075-T6 billet aluminum, machined on our own CNC machining centres in Tennessee and finished in black Type III hardcoat anodize (MIL-A-8625 Type III, Class 2). 7075-T6 has roughly twice the yield strength of 6061.

Yes. Every CMT lower takes a standard mil-spec lower parts kit and buffer assembly. The receiver extension threads and pin holes are held to spec, and the flared, broached magwell drops a mil-spec magazine cleanly. Build it in a proper vise block and never clamp on the magwell.

A matched lower and upper, cut from 7075-T6 billet and finished together as a set, so the fit at the takedown and pivot pins is right the first time and the finish matches. The set includes a serialized lower, so the whole set ships to your FFL.

UPS only, with a signature required on delivery, and only after we have confirmed your dealer's licence. USPS services and free-shipping thresholds do not apply to an order that contains a serialized receiver. FFL items leave within three or more business days of us receiving the dealer's licence.

Not once your dealer has transferred it to you. A firearm cannot come back as stock, so there is no return, exchange or refund for a change of mind, fit or finish. A defect in materials or workmanship is covered by the limited lifetime warranty as an exchange only, shipped through a licensed dealer. A wrong item or damage in transit is resolved the same way.

Match the rail to the barrel length and the gas system. From the product pages: a 7.5–10.5 in. barrel on a pistol gas system takes a 6.7 or 7.125 in. rail; a 10.5–11.5 in. carbine-gas barrel takes a 9.125 or 9.5 in. rail; an 11.5–14.5 in. carbine-gas barrel takes a 10.5 in. rail; a 12.5–14.5 in. carbine or mid-length barrel takes an 11.5 in. rail; a 14.5–16 in. mid-length barrel takes a 12.5 in. rail; a 16 in. mid-length barrel takes a 13.0 or 13.7 in. rail; a 16–18 in. mid-length or rifle-gas barrel takes a 15.0 in. rail; and an 18–20 in. rifle-gas barrel takes a 17 in. rail. Every product page states its own barrel range and gas system.

Every CMT handguard ships with the CMT barrel nut, and that nut does not have to be timed: there is no shim stack to chase and no clocking the nut to clear the gas tube. Torque the nut to the value in the instructions, confirm the gas tube passes through it without contact, slide the rail on and clamp it. That removes the most common cause of a canted rail, and the same nut comes back off for barrel work without a fight.

The handguard, the CMT barrel nut and the clamp hardware. The nut has wrench flats sized for a standard armorer's wrench. You supply the upper receiver, barrel, gas block and gas tube.

Every CMT handguard clears a low-profile gas block up to a .750 in. journal diameter. None of them clears a standard A2 front sight base or a clamp-on gas block with an oversized body. Verify gas-block alignment before the first live round.

They share the same free-float design, a continuous MIL-STD-1913 top rail that indexes flush with a flat-top upper, and the CMT barrel nut. The names are the profile and the finish. UHPR HDX and HDM rails are black Type III hardcoat; DRT and TANO rails are hardcoat anodized in earth tones, DRT in its dirt tone and TANO in CMT's Tanodized tone, and those shades vary slightly from batch to batch. Within the UHPR line, MOD 2 is M-LOK on every flat with nitrided steel QD sockets at 3 and 9 o'clock, MOD 3 is a full quad rail, MOD 4 is a hybrid with Picatinny at 3, 6 and 9 o'clock and M-LOK between, the A2 and ARCA rails carry an integrated ARCA-Swiss dovetail along the bottom, and the HP 308 rails are the AR-10 pattern.

Yes. The UHPR MOD 2-HP 308 rails (11.9, 13.7 and 15.0 in.) and the ARCA-HP 308 rails (15.0 and 17.0 in.) fit AR-10, DPMS and SR-25 pattern flat-top uppers. Every other CMT handguard is for a mil-spec AR-15 flat-top upper.

6061 extruded aluminum, machined in Tennessee and finished in Type III hardcoat anodize (MIL-A-8625 Type III, Class 2). Receivers are 7075-T6 billet; the two parts carry different loads and are cut from different stock.

If you can torque a barrel nut with the upper in a proper vise block and a reaction rod, you can install a CMT rail yourself. If you are not equipped for that, have a qualified gunsmith do it. Either way, confirm the gas tube clears the nut and the gas block is aligned before firing.

Plan B is CMT's suppressor-mount line: flash comps and brake comps threaded 1/2–28 or 5/8–24 for the barrel, each with a .900–24 right-hand mount thread and a 25-degree inclusive taper on the suppressor side. The Plan B HUB Mount Adapter threads onto that mount, seats on the taper for a gas-tight seal, and carries the 1.375–24 HUB thread into the suppressor. We make the parts here and sell them on cmttac.com and at planbmuzzledevices.com.

The one your barrel actually has. 1/2–28 is common on .224-caliber barrels and 5/8–24 on .308-caliber barrels, but caliber alone does not identify a thread: confirm it from the barrel manufacturer or by measurement. Both Plan B pitches use the same .900–24 mount, so one HUB Mount Adapter fits either.

A flash comp is the compact, no-timing choice for distorting visible flash during unsuppressed use. A brake comp redirects gas and reduces recoil during unsuppressed use and has to be timed with the matching 1/2-inch or 5/8-inch ID peel washer. Under a suppressor the mount is the same on both, so choose for how the rifle is shot unsuppressed.

No. HUB is the suppressor's rear interface, commonly a 1.375–24 internal thread. Plan B is the mount's connection to a compatible muzzle device. The Plan B HUB Mount Adapter bridges the two; a Direct-Thread HUB Adapter instead connects a HUB suppressor straight to a confirmed 1/2–28 or 5/8–24 barrel thread. They are alternatives, not stacked parts.

Checkout offers several services, each at its own price. When the free-shipping offer is running, the bar under the site navigation shows the USPS subtotal thresholds; a threshold is measured on the merchandise subtotal after discounts and before tax, and an order that reaches it exactly qualifies. UPS and FedEx services are always charged, and an order with a serialized receiver ships UPS only.

Non-FFL orders placed before the daily cut-off ship within one business day; allow two. Serialized receivers ship after we have confirmed your dealer's licence, typically within three or more business days of receiving it. Tracking is emailed when the carrier has the package.

Unused, uninstalled parts in their original condition and packaging can be returned within 30 days of delivery. Approved returns get a prepaid return label by email and there is no restocking fee; refunds go back to the original payment method, typically within four business days of approval. Installed, fired or modified parts, firearms and blemished parts cannot be returned.

Cross Machine Tool warrants each CMT product to the original purchaser against defects in materials and workmanship for the life of the product: a limited lifetime warranty. If a part fails because we made it wrong, we repair it, replace it or refund it, at our option; for a firearm the remedy is exchange only, through a licensed dealer. It does not cover improper installation, the wrong thread pitch or fitment, over-torquing, modification, misuse, normal finish wear or erosion from firing.

Use the Start a return link in the footer, or email orders@cmttac.com with your order number and a description or photo of the defect. Do not ship anything back until you have a return authorization from us. CMT prepays the return shipping on an approved claim.

A cosmetic second: a part with cosmetic or machining marks only, full function, sold at a discount and labelled as a blem on its own page. Blems are final sale, so there is no return, exchange or refund for how the part looks, but the limited lifetime warranty against defects still applies, and so do your rights if the wrong item arrives or it is damaged in transit.

The earth-tone hardcoat shades vary slightly from batch to batch. That is the nature of the anodizing process, not a defect, and it is why matched receiver sets are finished together as a set rather than pulled from two runs.

Yes. Verified FFL dealers get 20% off list on their own account, with no order minimum; promotions and sales do not stack with dealer pricing. Apply through the dealer account form and we confirm the licence before the pricing switches on.

Bulk orders start at 100 units per product. Private-label handguards in the HDM or UHPR style under your own mark start at 1,000 units, always on the CMT barrel nut and clamp locking system. Send the build through the OEM and volume page and we quote from the print.

Programmed, machined and finished under one roof in Tennessee by Cross Machine Tool Co., Inc., a veteran-owned business. We do not job parts out and we do not put our name on somebody else's part.

Email support@cmttac.com, or use the Contact support link in the footer. Fitment questions go to people who have installed these parts, and they write back themselves.