First Look: Ultra-Compact SIG SAUER MPX Copperhead 9mm – Review

SIG SAUER MPX Copperhead
SIG SAUER MPX Copperhead

U.S.A.-( I was very excited when SIG SAUER first sent out their press release for the new MPX Copperhead. The gun was so startling in appearance that I thought it was a hoax at first. When it proved to be the real deal, I heard that it was a dangerous prank aimed at mall ninjas. I had to find out just what the Copperhead was all about.

SIG MPX Copperhead

The MPX Copperhead version I received is the pistol variant and is chambered in 9x19mm. It comes with a telescoping brace which SIG has dubbed the Pivoting Contour Brace (PCB), but can mount a stock should you with to register the gun as an SBR.

Pivoting Contour Brace (PCB)
Pivoting Contour Brace (PCB)

The most distinctive feature is the super-short 3.5” barrel, which is less than a half inch longer than SIG’s revolutionary P365 pistol. A local ‘expert’ who occasionally offers unsolicited opinions to me stated that the Copperhead was so short that it was certain to blow your hand off if you held it wrong. “You can’t hold it without putting your hand in front of the muzzle,” he stated to me.

Super-short 3.5" barrel
Super-short 3.5″ barrel

I have heard from a number of these experts that the Copperhead is too small to do anything worthwhile and that it is meant for extreme CQB scenarios in the hands of the most elite military and police units and is not an accurate or practical gun for anyone to own. This is all false.

The Copperhead is an extraordinary little gun that will be sure to impress anyone that handles it. The extremely compact size and micro-length barrel make the Copperhead very easy to control and shoot accurately. The MPX platform is somewhat overbuilt as a product family, but they are very, very well made. While the Copperhead could be a pound lighter, it is not overwhelmingly heavy at 4 ½ lbs. The balance is at the center of the gun and it points well.

Scalarworks PEAK sights
Scalarworks PEAK sights

I did all my testing using an awesome set of Scalarworks PEAK sights. These are probably the best AR-style iron sights made today and I swear by their reliability, simplicity, and ruggedness. The sights are exceedingly easy to zero and boast toolless adjustment.

Some of you may scoff at putting irons on such a small gun but don’t knock it until you try it.

SIG SAUER MPX Copperhead

With my sights in place, I zeroed the Copperhead at 25 yards using Black Hills 115gr FMJ ammunition. The groups at 25 yards were very small, with the average being five shots into less than an inch. I set my elevation for a six-o-clock hold and went about doing a number of drills. The nice part about the Copperhead is that it is fully ambidextrous and the brass ejects somewhat forward, so there is no hot metal in your face while shooting left-handed.

The recoil impulse is very low and follow-up shots were fast and easy to make. I noted here that the stock trigger this gun comes with is a bit heavy for how light and small the overall package is, but it should be said that SIG sells match versions of the MPX trigger, so the fix is readily available. Pull was not terrible, but it did smooth out with use and I got quite familiar with it to where I did not notice.

The Copperhead is not just a short range gun. I walked it out to 50 yards on silhouettes and on a steel plate. The gun had no issues with hitting anything at 50 yards. I put some more distance between myself and the plates and began firing at 100 yards. The groups opened up, but not as much as you would expect. With the Black Hills 115gr FMJ I was still getting groups in the 4-6” range, but that was about to change when I chambered another Black Hills product.

SIG SAUER 365 115gr V-Crown
SIG SAUER 365 115gr V-Crown

The 100gr HoneyBadger +P is a load I have great familiarity with and I think it is one of the best standalone 9mm offerings made today. Not only is it a technologically advanced, it is accurate and fast. This load cut groups in half to the 2-3” range from the bench at 100 yards. I was easily able to ring steel with it over and over again.

In addition to the two Black Hills loads, I tested and chronographed a number of loads from Hornady, SIG, Black Hills, and Buffalo Bore. Groups are the result of three five-shot groups at 25 yards off the bench. Velocity is the average of ten shots measured five feet from my Oehler 35P chronograph.

  • SIG SAUER 365 115gr FMJ——————————1075fps, .75”
  • SIG SAUER 365 115gr V-Crown————————1076fps, .75”
  • SIG SAUER 124gr V-Crown—————————–1150fps, 1.0”
  • SIG SAUER 115gr V-Crown—————————-1190fps, 1.25”
  • Black Hills 115gr FMJ———————————–1080fps, 1.0”
  • Black Hills 100gr HoneyBadger +P——————1190fps, 1.0”
  • Black Hills 125gr Subsonic HoneyBadger———-980fps, 2.0”
  • HSM 115gr JHP——————————————1175fps, 1.75”
  • HSM 115gr XTP—————————————–1180fps, 2.0”
  • HSM FMJ————————————————-1110fps, 2.0”
  • Hornady 135gr +P Critical Duty———————1050fps, 1.75”
  • Hornady 124gr +P Critical Duty———————1138fps, 1.5”
  • Buffalo Bore 147gr JHP +P+————————-1075fps, 2.0”

I fired about a thousand rounds through this cool little gun and I experienced not a single malfunction. In addition to this, I opened the gun up and was surprised to find that it was completely clean on the inside. The interior looked exactly like when I first looked at it out of the box. Every modern shooter knows how filthy the standard AR pattern rifle gets after just a couple hundred rounds so you can imagine how pleased I was.

Now, some of you may want to know just how much of a liability the super short barrel was during my testing. In short, it was not a problem. The whole ‘your hand will slip in front and you’ll get shot’ thing is just not possible. There is no real estate to mount any sort of grip or knuckle guard, but it’s not like you’re going to hold this miniscule gun the same way you hold a full-size rifle or carbine. My grip was simply on the front of the magazine well and I never had an issue. You can feel some concussion in your hand, but it’s not painful or distracting.

Ultra-Compact SIG SAUER MPX Copperhead
Ultra-Compact SIG SAUER MPX Copperhead

Overall I found the MPX Copperhead to be a fun little piece with a number of end uses. The casual shooter may struggle to grasp it, but I see a number of end uses in the woods and for defense in the home. The gun is far too large to be carried on the body, but it would easily fit in a pack or in your underwear drawer. You have your choice as far as optics or sights and you can easily mount a light or laser.

The nice part about this gun is that it is easy to handle and has the same manual of arms as most AR rifles. A small-statured shooter would do well to take advantage of the low recoil and blast in the home. The Copperhead offers a compact size with magazine capacities that exceed most all handguns in the same caliber.

SIG SAUER has a winner here. The ultra-compact Copperhead is in a class of its own when it comes to accuracy and features. If this isn’t your deal, I suggest you go fire one and perhaps your mind will change. If you’re shooting inside 100 yards, there is probably no other gun that offers the accuracy, portability, and ease of use as the MPX Copperhead.

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About Josh WaynerJosh Wayner

Josh Wayner has been writing in the gun industry for five years. He is an active competition shooter with 14 medals from Camp Perry. In addition to firearms-related work, Josh enjoys working with animals and researching conservation projects in his home state of Michigan