BCM MK2 Buffer Mod 1 for AR-15
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Fits the BCM MK2 receiver extension only, and must be used with a Mil-Spec M16 rifle action spring. Will not fit a standard carbine receiver extension and must not be run with a carbine spring. If you do not already have an MK2 receiver extension fitted, buy the complete MK2 Recoil Mitigation System Mod 1 instead, which includes this buffer.
Not sure it fits your rifle? Ask us before you order
The BCM MK2 Buffer Mod 1 is a bare intermediate-length buffer for AR-15 and M4 rifles, sold on its own for shooters who already run the BCM MK2 receiver extension.
This is the buffer only — no receiver extension, no spring, no castle nut, no end plate. It is the replacement or re-weighting part for an MK2 system you already own.
Read that first line twice before ordering, because the two BCM part numbers look alike and are not alike. This listing is the bare BFMK2 buffer. If you do not already have a BCM MK2 receiver extension and a Mil-Spec M16 rifle action spring in the rifle, this part will not fit anything you own — you want the complete MK2 Recoil Mitigation System Mod 1, which contains this same buffer along with the tube, the rifle spring, the castle nut and the QD end plate.
What you get is the mechanism itself. The MK2 buffer is machined from 7075-T6 aluminium and hard-coat anodised, and it runs a longer internal counterweight travel than a carbine buffer with an internal spring to quieten the counterweight as it shifts. Longer travel means less bolt bounce and a more consistent carrier velocity, which BCM covers under US Patent 10415907.
Buffer weight is the tuning lever. T2 is 5.6 oz (160 g) and T4 is 7.4 oz (210 g), and the heavier the buffer the more mass has to be moved and returned on every stroke. On a UK straight-pull AR-15 that stroke is worked by hand, so buffer weight and spring rate directly set how the action feels under the palm and how positively the carrier returns to battery — the shooter is the cycling mechanism, and they feel this component every single time.
This buffer fits the BCM MK2 receiver extension only, and must be run with a Mil-Spec M16 rifle action spring. It is not a carbine buffer and will not work in a standard carbine receiver extension, and a carbine spring must not be substituted — BCM is explicit that incompatible components can damage the rifle and injure the operator. If you are starting from a standard carbine buffer system, buy the complete MK2 Recoil Mitigation System Mod 1 instead; it includes this buffer plus everything else the conversion needs. One further note on the MK2 tube itself: because it is roughly ¾" longer than a carbine extension, some Mil-Spec stocks will not collapse all the way back to the castle nut.
| Platform | AR-15 / M4 |
|---|---|
| Fits | BCM MK2 receiver extension with a Mil-Spec M16 rifle action spring — nothing else |
| Type | Buffer only — intermediate length, bare component, no tube or spring included |
| Material | 7075-T6 aluminium |
| Finish | Hard-coat anodised |
| Weight | T2 5.6 oz (160 g) · T4 7.4 oz (210 g) |
| Brand | Bravo Company USA |
| MPN | BCM-BFMK2-M1-T2 · BCM-BFMK2-M1-T4 |
Only buy this if the MK2 tube is already in the rifle. Order the MK2 Buffer Mod 1 today — imported from the USA with all duties paid by us and dispatched tracked from the UK in 7–10 business days, with nothing to pay on delivery.
Explore more: AR-15 Parts & Accessories, Rifle & Shotgun Stocks or browse all Bravo Company USA.
| Platform | AR-15 / M4 |
|---|---|
| Fits | BCM MK2 receiver extension with a Mil-Spec M16 rifle action spring — nothing else |
| Type | Buffer only — intermediate length, bare component, no tube or spring included |
| Material | 7075-T6 aluminium |
| Finish | Hard-coat anodised |
| Weight | T2 5.6 oz (160 g) · T4 7.4 oz (210 g) |
| Brand | Bravo Company USA |
| MPN | BCM-BFMK2-M1-T2 · BCM-BFMK2-M1-T4 |
| Category | Lower Parts |
| Barcode | 812526023070 |
£5 tracked UK delivery on every order via Royal Mail Tracked 24. Our products are ordered in from the manufacturer rather than held in UK stock, so please allow 7 to 10 business days (Monday to Friday, excluding bank holidays) from the date of your order for it to reach you. Tracking details are emailed on dispatch. UK delivery only.
You have 30 days from receiving your order to cancel it for any reason, then 14 days to send it back unused and in its original packaging. Faulty, damaged or incorrect items are replaced or refunded and we cover reasonable return postage. Refunds go back to your original payment method within 14 days of receiving the return.
Just the buffer. This listing is the bare BFMK2 component — there is no receiver extension, no action spring, no castle nut and no end plate in the box. The complete kit is the <a href="/products/bcm-mk2-recoil-mitigation-system-mod-1">MK2 Recoil Mitigation System Mod 1</a>, which contains this same buffer plus all four of those parts.
No. The MK2 buffer is intermediate length and is designed for the BCM MK2 receiver extension with a Mil-Spec M16 rifle action spring. It will not work in a carbine receiver extension, and BCM warns that running incompatible buffer, spring and tube combinations can damage the rifle and injure the shooter. Check what is in your rifle before ordering.
T2 is 5.6 oz (160 g) and T4 is 7.4 oz (210 g). Heavier means more mass to move and return on each stroke; lighter means less. If you are replacing a buffer in an existing MK2 system, match or step from what you already have. If you are unsure which weight is in your rifle, weigh the buffer you take out.
Because you are the cycling mechanism. Buffer mass and spring rate govern how the carrier returns to battery and how the whole action feels as you work it, so the buffer is a component you feel on every stroke rather than one that only matters under gas.
Buffers are sent from the United Kingdom with £5 tracked UK delivery in 7–10 business days, and you will get tracking by email when it ships. If a part turns out to be the wrong fit, see our returns policy or <a href="/pages/contact">contact us</a> and we will help sort it.
7 to 10 business days from the date of your order. Every order is sent Royal Mail Tracked for a flat £5 and you receive tracking details by email when it is dispatched.
Yes. We list only genuine parts and optics from the brands shown, ordered in from the manufacturer for your order.
Compatibility notes on this page come from the manufacturer. If you are unsure, email us with your make and model before ordering and we will check rather than guess.
Yes. Bundle & Save applies automatically in your basket: 5% off when you buy 2 items, 10% off at 3 items and 15% off at 4 or more. It works across the whole range, so you can mix and match, and there is no code to enter.
Yes — you have 30 days from delivery to cancel for any reason, as long as the item is unused and in its original packaging. See our returns policy for the details.
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