Are M-LOK and KeyMod accessories interchangeable?
No. KeyMod uses a keyhole opening and M-LOK a rectangular slot with a rotating T-nut. Neither system’s hardware mounts to the other.
They are two separate attachment standards that solve the same problem in incompatible ways. No KeyMod accessory mounts directly into an M-LOK slot, or the reverse — the hardware simply does not engage. What does exist are small adapter sections that bolt into one system and present the other, so a KeyMod accessory can reach an M-LOK rail through an intermediate part. That is a conversion rather than interchange, and it adds height and a second interface to check.
| KeyMod slot | Keyhole — insert through the round end, slide, tighten |
|---|---|
| M-LOK slot | Rectangular — T-nut drops in and rotates 90 degrees |
| Direct hardware interchange | None — needs an adapter section |
| M-LOK origin | Developed by Magpul |
| Practical default | M-LOK — far wider industry support today |
If you are choosing rather than matching something you already own, M-LOK is the safer bet: it has the broader accessory ecosystem, and KeyMod support has thinned considerably. If you already have a KeyMod handguard and a drawer of KeyMod mounts, there is nothing wrong with it — just buy hardware that matches the rail in front of you.
Caution: Check the slot shape on the handguard before ordering, not the product title. Listings routinely describe a handguard by the wrong standard, and the two are unmistakable once you look at the openings.
Sources
Last checked 2026-09-02. Specifications change between production runs — verify anything safety-critical against your own firearm and the manufacturer before acting on it.
More on AR-platform parts
- Will an AR-15 upper fit an AR-10 lower?No. An AR-10 lower is a physically larger receiver. Worse, AR-10 has two incompatible patterns that do not mix with each other either.
- Will a mil-spec AR-15 stock fit a commercial buffer tube?No. A commercial tube is about 0.022 inches fatter, which is enough that a mil-spec stock will not slide on. The other direction fits but rattles.
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