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Every AR-9 builder knows the sound: that metallic sproing rattling down the buffer tube every time the action cycles. The Armaspec SMB-9 Buffer Kit takes that off the table by combining the Gen3 Sound Mitigation Buffer with the receiver extension, end plate, and castle nut you need to finish a lower. Instead of chasing down separate parts and hoping they play nice together, you get a matched set that installs in a few minutes and runs quieter right out of the gate.
The heart of the kit is the SMB itself, a single-stage captured design that replaces your standard buffer and spring in one piece. What makes it different is how the spring is kept from dragging along the inner wall of the buffer tube, which is where most of that noise and gritty vibration comes from. The result is a smoother, quieter cycle and a noticeable drop in the harsh twang you get from a mil-spec setup. It's built in the U.S.A. and backed by Armaspec's lifetime warranty.
This version is weighted around 6.8 oz, tuned specifically for the heavier bolt carriers found in blowback 9mm builds. One thing worth knowing up front: the SMB-9 is made for 9mm bolt carrier groups, and the extra weight on the back of the carrier needs to come off for proper function. It's held on by a spring/roll pin, so it's a quick job. Unlike the rifle-caliber SMB weights, the 9mm weight isn't swappable, so this one's dialed in for the pistol-caliber platform.
Installation is about as simple as it gets. The polymer base with the guide rod drops into the buffer tube, the spring slides onto the rod, and the buffer goes over the spring. If you're tuning your gun, the main spring can be trimmed at roughly a quarter pound per coil to lighten tension, up to twelve coils. Give it about 100 rounds to fully set, and you'll feel the difference over a factory buffer and spring on a budget-friendly upgrade that punches well above its weight.
The kit pairs the Armaspec Gen3 SMB-9 Sound Mitigation Buffer with a buffer tube, end plate, and castle nut. That's everything you need on the receiver extension side to finish an AR-9 lower in one purchase. No need to source the hardware separately or worry about matching parts.
Yes, the SMB-9 is designed specifically for 9mm bolt carrier groups. Keep in mind you'll need to remove the extra weight on the back of the carrier for it to function properly. That weight is held on by a spring/roll pin, so it comes off quickly with basic tools.
No, the weight on the 9mm version is fixed and comes in around 6.8 oz, tuned for blowback pistol-caliber builds. Only the rifle-caliber SMB weights (C, H, H2, H3) are interchangeable. If you want to fine-tune the feel, you can still trim the main spring to lighten the tension.
Not at all. It's a drop-in design: the polymer base and guide rod go into the buffer tube first, then the spring onto the rod, then the buffer over the spring. Give it roughly 100 rounds for the spring to fully set, and the whole swap takes only a few minutes.
| UPC | 810048492763 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | ARM268-9 |
| Color | Black |
| Model | |
| Product Type | Buffer Tube Complete Assembly |
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