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Sig Sauer MCX Rattler Has 1 Big Fatal Flaw

Sig Sauer MCX Rattler
Sig Sauer MCX Rattler. Image Credit: Creative Commons.

Sig Sauer MCX Rattler: A Great Firearm with One Really Awful Trigger?

Sig Sauer has done it once again.

The Sig Sauer MCX Rattler, chambered in 300 Blackout, is a fantastic platform with a price tag that made me cry on the inside. It’s a firearm that wins huge on style points but is held back by one issue for me. It’s certainly worth buying, but a disclaimer should be attached to it.

Let me preface this by saying that I don’t go for pre-built rifles or AR pistols too much these days since I really enjoy putting things together and getting a little bit more control in the building process. It usually ends up a little cheaper too.

I purchased the pistol configuration of the MCX Rattler since I wasn’t keen on waiting on a tax stamp for a short-barrelled rifle (SBR). Still, the Rattler looks extremely clean. It’s compact and easy to store in a backpack or even under the seat of a car. I personally found myself actually keeping it beside my bed since the short barrel length (5”) is perfect for maneuvering the tight hallways and doorways of my house. It comes furnished with a blocky M-LOK handrail that looks really good as well as a stabilizing brace which is frankly trash. It’s unstable and wobbly. I can’t stand it. Aside from that, every non-actuating part of this AR pistol is solid.

Sig Sauer MCX Rattler and That Trigger

I do want to talk about the trigger first though. It’s pretty terrible. It’s clunky, gritty, and heavy. I do not enjoy a 9lb trigger pull on my rifles or AR pistols, or basically any firearm really. It makes shooting accurately so much tougher at longer distances. This is one of those issues that really bogs this rifle down. I’m definitely going to have to swap it out to make it bearable.

If you’re looking past that though, the accuracy is actually pretty good. I threw on a little red dot sight and was really only trying to engage at fifty yards. Groups were solid with three-inch groups while doing some casual shooting. Out past that, I was able to maintain 3 MOA while seated and focusing hard. I usually won’t go out past that if I’m not using a Low-Powered Variable Optic (LPVO) or some kind of magnified optic and a scope frankly just looks goofy on this thing.

Outside of that, I don’t know what else I could ask for. It’s ergonomic, maneuverable, and super quiet with subsonic ammo and a suppressor. Plus this gun was originally made for military and special operations so it definitely scratches that itch. I was able to find a practical use, but there are some significantly cheaper options out there, even if they don’t look quite as cool.

I won’t say it’s a straight-up go and buy this right now, but I’m pretty sure you won’t be disappointed if you pull the trigger on this one.

Richard Douglas writes on firearms, defense, and security issues. He is the founder and editor of Scopes Field, and a columnist at the National Interest, 1945, Daily Caller, and other publications.

Written By

Richard Douglas is a long-time shooter, outdoor enthusiast, and technologist. He is the founder and editor of Scopes Field, and a columnist at The National Interest, Cheaper Than Dirt, Daily Caller, and other publications.



  1. W. Harrell

    December 28, 2021 at 12:05 pm

    It’s not a rifle, it’s a pistol.

  2. Brian Patronie

    December 28, 2021 at 1:04 pm

    How much?

  3. Comanche

    December 28, 2021 at 2:04 pm

    Retail is about $2,200.00!!!%

  4. Shane Davis

    December 28, 2021 at 7:34 pm

    So $2200 for the Sig MCX Rattler with a bad brace and iffy trigger. OK, but those can be upgraded to the some of the best there is for just another $575; about $350 for a Geissele Super MPX SSA trigger and $225 for a Modern Warriors Collapsing stock.

    Now you about $2775 into the Sig as opposed to $3200 for the stock FN SCAR 16S, but the MCX will have one of the best triggers, a great stock, you can use any generation of Magpul mags and it doesn’t have the over heating issue. Oh, and it’ll still be $1000 cheaper.

    I know you raved about the SCAR, but in the real world for the amount of money one would lay out for the SCAR, I could get the MCX and up grade to the Geissele trigger and the MW stock. Put on a Leupold LCO optic and I’m at $3400, which is just a two or three hundred over the real world price of about $3200 for the SCAR, and I’ve got a far superior trigger, outstanding optic, great stock and a smaller, easier to maneuver around with unit.

    It’s all preference and opinion when it comes to the big name firearm makers, but for the same cash it looks to me the MCX is a better value than the SCAR. But again, just an opinion.

  5. Shane Davis

    December 28, 2021 at 7:36 pm

    CORRECTION: “It’ll still be $500 cheaper” …. my math isn’t that bad, but rather my bear paw sized hands just love to sneak in typos that I don’t catch until it’s too late. Beg pardon.

  6. Kurt

    December 29, 2021 at 12:09 pm

    Yah, Sigs quality control has a lot to be desired lately. I sold the MCX, and went back to BCM. Also, nato rounds make more sense to me, I like 308, 223/5.56, and of course 7.62X39 if you had bought 30K rounds back at .16 cents a round. These M4/AR15 platforms that add a piston system have more working parts, just means more to go wrong. The FN Scar is a revolutionary system, and in 308 hits hard. And good luck finding and shooting 1000s of rounds of 300. My .02


    January 9, 2022 at 9:14 pm

    I have the Rattler and I love it but that trigger isn’t the greatest. A friend I know has the Rattler has replaced the trigger with a Timney Trigger and love it.

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