SIG MCXの問題点:レールが曲がって照準が狂う



私はKeyModのMCXレガシー(第1世代)を持っていて、レールの先端にMAWL(レーザー)を装着している。最近、レールに2~3 MOAほどの「しなり」があることに気づいた。障壁から撃つとき、銃のマグウェル付近を支えると、レーザーはスコープの照準と一直線になっている。しかし、ハンドガードの先端近くを手で持って支えると、レーザーが2~3 MOAほど上にずれる。スコープを覗くと、レーザーが動いているのがわかる。

MCX Top Rail Flexing (2019)




2021年12月、Primary & Secondaryの有識者会談で「レーザーの手前置き」が話題になったとき、インストラクターのマーク・スミス氏が次のように述べた。

This is significant only to the MCX platform, so far as I have experienced in my shooting career. I hung out with some dudes from Bragg, some dudes you may know, Unit guys and whatnot, with the LVAWs and such a 300 Blackout system. Even though they’ve got the fancy rail and upper receiver that I can’t get, the two guys that I know, both told me that “Man, this thing sucks for rail flex,” blah blah blah. My citizen version is like dog balls, it’s a no-go. You put a laser out on the end of MCX, if you bump that thing on a tree, you have now lost zero to the point of eight inches at 50 yards. It’s terrible.


The Unit guys that I saw sitting around a dude’s island in his house one time, they both had their LVAWs with the NGALs mounted toward the rear of the barrel nut, because they had to. You can’t do it. But the MCX is, in my opinion based on the 300 Blackout platforms I’ve messed with, is the superior 300 Blackout platform. They’ve figured it out. If that’s what you’ve got to use, that’s what you want to use, whatever, then that’s what you’ve got to do as of right now, because there ain’t a solution yet. I may have seen some pictures of some stuff, maybe there’s a fix, that’s on the horizon, but you know what that means. Five years from now, maybe. But as of right now, the fix is you’ve got to get that thing back, if you put it on the end of the rail, you might as well not have it.

P&S ModCast 279.3 – Aiming Lasers at the Nut (2021)



Sig MCX Virtus (2017)


The MCX Virtus handguard is secured to the receiver by a friction fit slot on each side near the extended receiver top rail and a single steel fitting held in place by the front takedown pin. This allows the handguard to flex significantly, causing a laser or front sight zero to change when minor pressure is applied to the handguard. A shift of 5 mils or more is possible by pushing on the handguard with your support hand while the rifle is shouldered. Additionally, the zero does not always return to it’s original position once pressure is removed from the handguard.

Arisaka MCX Zero Retention Clamp (2022)