The BCM Milspec Carbine Stock Hardware Mounting Kit is a complete receiver extension assembly for AR-15 and M4 rifles — buffer tube, receiver end plate, castle nut, carbine action spring and carbine buffer — and it does not include a stock.
Bravo Company USA's name for this kit mentions a stock, and some retailers list the same part more plainly as a buffer tube assembly, which is what it actually is. You get the Mil-Spec 6-position receiver extension machined from 7075-T6 aluminum, the receiver end plate, the M4 castle nut, the carbine action spring and the carbine buffer assembly. Bolt those to a lower receiver and you have everything a Mil-Spec stock needs to slide onto — except the stock.
That makes it the right purchase when you already have a serviceable stock and want fresh, correctly specified hardware behind it, or when you are building a lower from parts and want the tube assembly from one manufacturer. If you want the stock as well, the Gunfighter Stock Kit Mod 0 in Black is this same hardware supplied with the Mod 0 stock fitted. Ordering this kit expecting a stock is the most common mistake with this part, so double-check which one you need.
Key Features
- Hardware only — for the Mil-Spec stock you already own
- 7075-T6 receiver extension — 6-position, machined to Mil-Spec dimensions
- Complete assembly — tube, end plate, castle nut, action spring and buffer in one box
- Matched components — spring and buffer specified together rather than mixed from a parts bin
- Broad stock compatibility — takes Mil-Spec stocks from a range of makers
Compatibility & Fitment
Fits AR-15/M4-pattern lower receivers with a standard threaded rear. Bravo Company USA lists the kit as compatible with Mil-Spec dimension stocks from BCM, VLTOR, LMT, Magpul CTR-M, Stag Arms and Colt. Because the receiver extension is Mil-Spec diameter, a commercial-diameter stock will not fit it. Remember that no stock is supplied: you must already have one, or buy one separately. Fitting needs a castle-nut wrench, and the castle nut should be torqued and staked or thread-locked.
Technical Specifications
Platform | AR-15 / M4 |
Fits | AR-15/M4 lower receivers with a standard threaded rear; Mil-Spec dimension stocks |
Type | Stock mounting hardware — receiver extension, receiver end plate, castle nut, carbine action spring, carbine buffer. No stock included |
Material | 7075-T6 aluminum receiver extension |
Adjustment | 6-position receiver extension |
Brand | Bravo Company USA |
US Shipping & Support
Shipped from D&R Sports Center in the USA with fast, tracked delivery. Questions on fit, mounting or which model suits your setup? Our team is glad to help before and after your purchase.
Frequently Asked Questions
Does this kit include a stock?
No. Despite the name, there is no stock in this box. You get the receiver extension (buffer tube), receiver end plate, castle nut, carbine action spring and carbine buffer only. If you want the same hardware supplied with a stock, choose the Gunfighter Stock Kit Mod 0 in Black instead.
Which stocks will fit this tube?
The receiver extension is Mil-Spec diameter, so it takes Mil-Spec dimension stocks. Bravo Company USA lists compatibility with stocks from BCM, VLTOR, LMT, Magpul CTR-M, Stag Arms and Colt. Commercial-diameter stocks are slightly larger and will not fit, so check what you have before ordering.
What tools do I need?
A castle nut wrench and a way to hold the lower receiver securely. The end plate goes on first, then the tube threads in, the buffer and spring drop in, and the castle nut is torqued and staked or thread-locked against the end plate. If you would rather not do that yourself, have a gunsmith fit it.
