A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

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A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The Sig Sauer X-Five Full Size is a 21+1 capacity 9mm designed for competition and just a great all-around shooter in the author’s opinion.

Top gun makers have churned out so many variants of their products over the past few years that it can sometimes be hard to keep up. SIG Sauer has certainly done its part to use every possible combination of letters and numbers in their SKU collection, making my safe bulge and my wallet shrivel. And just when we thought they might sit back on their laurels for bit – along comes another configuration of the P320 Series – the “X”. Available in three configurations: X-Carry, X-Five, and X-VTAC (a Talo exclusive). While they are all true P320 pistols at heart, they each sport a newly designed and shaped polymer frame, each has some amount of lightening cuts in the slide, and each caters to a different purpose of use. This review focuses on the X-Five – the full-sized competition oriented model that will be the flagship of this trio.

My first thought when reading the breaking news of this new lineup (right here on GunsAmerica, of course) was that SIG was making some neat looking cosmetic changes to the pistol and maybe a bell here or a whistle there. It wasn’t until I received the test sample of the P320 X-Five and immediately tore it apart before I realized that the mad scientists at SIG had done much more than that! It is a P320, and shares the same internal serialized chassis (or fire control group) as the rest of the series. But in just about every other way it is a completely new and different gun.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.THE DESIGN AND SPECS

SIG has used the “X” moniker before, but for the P-Series steel framed pistols. Those guns are highly prized and jealously guarded by their owners. Bringing the “X” to a polymer framed gun certainly has created a high expectation. An expectation that I think SIG has met. Let’s look at the overall build info.

Currently available only in 9mm, the striker-fired X-Five is a noticeably large handgun. Its 8½ inches of overall length flirts with the limits of allowable dimensions for IDPA, but it is the 6½ inches of height that make it a no-go for that sport. IDPA rules state that a gun must fit in a standard box with specific dimensions with the longest magazine that will be used inserted in the gun. In the case of the X-Five, that magazine is a 21-round extended mag (of which a generous four are provided), which gives the gun its disqualifying height. I’ll talk more about magazines in a bit. The pistol tips the scale at 34.7 ounces with an empty magazine. That’s heavy for a polymer-framed gun, but there is a little secret lurking within that helps explain that. In the rear of the grip, just behind the magazine well (think of where a mainspring would be on a hammer-fired handgun) there is a block of metal inserted. I don’t know for certain the metallurgical composition of the material, but it is non-magnetic so it’s not steel. Add to that the extra heft of the bull barrel, and that helps explain why you’re over two pounds even with all that material removed from the slide.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The pistol has a blockier overall shape than the original P320 as well as numerous upgrades and enhancements.

Although the slide itself is barely more than 1-inch wide, the ambidextrous slide stop/release control puts the maximum width at about 1.350 inches. The enhanced beavertail certainly accounts for some of the overall length, but we are still given a nice long sight radius of 6.8 inches. And those sights are Dawson Precision with the rear fully adjustable for windage and elevation, and the front contains a bright but very fine fiber optic. As mentioned, SIG redesigned the frame of this pistol to be SIGnificantly different from the standard P320 lineup. The X-Five is squarer and consists of lines and angles rather than curves. The pistol has a different feel than that of its siblings. I like it, but I might prefer the rounder ergonomics of the standard P320. “Differently good” is probably the best I can do to describe it at this point.

SIG put a flat trigger in the X-Five, in holding with the tradition of that name. It is also very much like the flat triggers of the Legion pistols. There is something about the flat trigger that makes me feel as if I’m pulling the front sight directly through the rear notch much better than usual. It could be all in my head, but I think not. At the break, the trigger is perfectly vertical – and this just feels like a natural finish position to my finger. There is a flared magwell extension that is worthy of a race gun, and acts as a funnel in which you can shove the next magazine. It is easily removable for those times you don’t want it or can’t have it. The magwell is steel and will take punishment. The slide has been lightened via three rectangular cutouts in the top, which is done to assure that lighter powered loads (typical for competition) will still cycle the action even with a recoil-managing spring.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The X-Five comes with four 21-round magazines. That’s what I call match ready.

Shooting The P320 X-Five

The first thing I noticed when I started shooting the P320 X-Five was the sight picture. That makes sense, I suppose because that is where your visual attention tends to be, and your mind always gives priority to visual stimuli. But it also says a lot about what getting my attention, like the ergonomics of the gun. The X-Five slipped into my hand naturally and my finger found the trigger – right on the sweet spot. The hand goes up high on this gun naturally, and the elongated beavertail gives you a great wedge to lock into. The undercut trigger guard helps you keep the high hold with the best grip angle. So, with all of those important elements on auto-pilot for the time being I was able to concentrate on the sights. The Dawson Precision sights on the pistol are nice ones. The rear is a custom fit into the cutout that we’re told will accept the Romeo1 optic if the sight is removed. I have a P320RX and was able to eyeball that size and shape, and it looks like it would indeed fit. What I didn’t see was an easy way to remove the sight without making a project out it, so I did not test the theory. The rear Dawson is blacked out (my preference on a match gun) with anti-glare serrations. It is fully adjustable for windage and elevation. The front sight, also a Dawson, is very narrow with a fine green fiber optic installed. There is ample air space between the front blade and rear notch to really focus on those precision shots. The sights seemed pretty well zeroed out of the box.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The flat trigger measured just under 5 lbs. on my scale, and helps promote good trigger control.

At some point during the shooting, perhaps while doing some “two to the body, one to the head” drills – I began to really notice the balance of the X-Five. The pistol has a very well-engineered balance that feels like 50/50. But what impressed me was that as I ran through magazines loaded with 21 rounds the balance didn’t seem to change. The gun got lighter of course, but it felt like a boat lifting in a rising tide – the bow and the stern rose as one. My simple non-engineer mind attributes that to the combination of the very heavy bull barrel and the added weight that has been tucked into the backstrap of the grip. It is also my understanding that these weights could be user-changed. That could mean serious balance customization for competitors.


A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The Dawson Precision sights are very well suited to competition or target shooting.



A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

Helping with the weight and balance management of the X-Five are the lightening cuts in the slide.


A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.The accuracy potential of the pistol seems to be the precision that the target consumers will demand. However, I did notice a fairly wide spread in results with different brands and types. The best groups at 25 yards were produced with Speer Gold Dot and SIG’s own V-Crown JHP ammo, while surprisingly the SIG Elite Performance FMJ ammo was erratic. I never did pin it down to a particular bullet weight or design.

My advice is to put in the time to match the ammo to the gun and it will shoot ragged hole groups all day. My own handload competition ammo performed great, with 124-grain plated round nose bullets and just enough powder to qualify – this should be encouraging. Never could get the gun to malfunction, no matter what I fed it.


A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The X-Five shot the tightest three-shot group with the American Gunner ammo from Hornady



A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The pistol shot its tightest five-shot group with the Speer Gold Dot load.



I would be remiss if I didn’t offer some information and thoughts on the compatibility of the X-Five with the rest of the P320 line. First, holsters. If you have a P320 full size that came with a holster when you bought it – take heart, the X-Five will fit. There is a smidgeon of air space at the back of the trigger guard but the trigger is fully protected. The sight channel also is just barely large enough to accept the Dawson front sight, but it does. For my range work I used a Multi Holsters rig that was made for the P320RX, and it was a great fit. Magazines on the other hand, are not compatible between other P320s  and the X-Five. At least not easily. The box magazine is identical to the extended 21-round P320 mags, but the baseplates are different. They could be swapped out, but unless you have a large supply already it might not be worth trying to get baseplates. The good news is that you can use the X-Five magazine in the P320. So, if you have both – or plan to have both – be sure you buy 21-round X-Five magazines and you’ll be good. The X-Five also shares a number of other parts with its fellow P320s, including the serialized chassis. Might there be future kits available to build different X-Fives?

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The P320 X-Five is a serious competition package, not just a P320 “with extras”.

Just My Opinion

Seems like the X-Five is everything the hype indicated, and that’s not always the case in the firearms industry. This gun is not just a slight variant of the P320, but is really a redesign of the way this modular system can be employed. SIG is no stranger to competition, even though they have greatly reduced their footprint in that arena. The company has not abandoned the handgun competitor – quite the contrary, in my opinion. I think the X-Five demonstrates SIG Sauer’s willingness to offer a product to an enthusiastic segment that is not likely to drive high sales numbers. However, where I think SIG has missed the mark is to design a gun that disqualifies itself from IDPA, the leading shooting sport in terms of participation. Even with the magwell removed I could not use the 17 round magazine from a P320 in the X-Five. Swapping baseplates would not help because of the height of the plate. Perhaps flush-mount X-Five baseplates will be produced in the near future? I hope so, and I hope SIG sells them cheap. Or, perhaps they don’t want to compete with themselves and figure the P320 has already become a strong contender in IDPA (I see them everywhere) but a USPSA or Steel Challenge type gun was needed. I won’t second guess the development team on that one. You don’t make a gun with all 21 round magazines to go after the IDPA market, where the maximum capacity for any gun is 10+1.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

In addition to the usual P320 components, the X-Five sports a bull barrel, flat trigger, and speed magwell.

A Mega-Capacity Sig Sauer P320? The 21+1 Full Size X-Five 9mm – Full Review.

The 360-degree throating of the barrel all but guarantees no misfeeds.

If you’re a SIG enthusiast, you’ll want this gun. It’s nice – very nice. If you’re a USPSA or Steel shooter you need to give it a look too. There is much more to the P320 X-Five than first meets the eye.

For more information, visit https://www.sigsauer.com/store/p320-x-five-full-size.html.

To purchase a Sig Sauer P320 variant on GunsAmerica.com, click this link: https://www.gunsamerica.com/Search.aspx?Keyword=Sig%20320.

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  • Steven Lugeslia April 24, 2019, 12:27 am

    To make this gun legal in IDPA would weaken it for the other handgun shooting sports. I shoot 3 gun and Steel challenge and this gun is great for that. I am not looking for one gun to do it all and I think that is not a good way to design a gun. With this gun I make large holes in targets at the range. For steel it is great to not have to change mags each stage and it points naturally so I do better with this than my other guns.

    However I just bought a CZ TSO which costs about $800 more and is much heavier. However with its single action 1.5 lb. trigger it is a speed demon. I can hit targets at 25 yards like they were at 7 yards. With its light trigger and very short reset I can shave off time from my score. It too is designed for USPA and Steel. It is bad enough that even IDPA is being gamed and people are not using what they carry but rather what gives them a competitive edge.

  • Owen Weislow March 24, 2018, 5:38 pm

    Just wondering if the X-5 needs or would benefit from the same upgrade as other P320 chassis?

  • Gilbert Jimenez August 18, 2017, 6:20 pm

    Funny and looks silly that this gun is designed for competition and marketed as competition gun right out of the box but disqualifies itself from the biggest competition platforms like IPSC and IDPA. I wonder what the designers of this gun were thinking when they made their design decisions? Sig Sauer has even an ambassador who is an IPSC world champion, Max Michel. This Pistol caught my eyes at once and it’s a pity that it turns out to be useless specially for me as a shooter in IPSC standard and production division.

  • PaulWVa June 12, 2017, 10:13 pm

    Yeah…OK….I want one. I have two 9mm, P-320s now, a Compact, black/fde, night sights, Apex trigger, Streamlight TRL-3…my house gun. I also have a Sub-Compact, w/night sights and An Apex trigger for carry. I love these guns, they shoot well and are really easy to work on. Great accuracy for combat guns with short sight radius. I think this gun in a full size with adjustable sights would be a great piece for my Sig 320 collection. It’s obviously competition ready but I think the X5 would make a great steel plate gun or just a great range gun. The $grand.00 is a big bite but does come with $200.00 in mags. On the other hand my best shootin’ buddy picked up the new 320 RX with Romeo 1 red dot for $750.00. I’ll be watching for shelf price of the X5. Yeah…I WANT ONE!

  • Rick June 12, 2017, 10:13 am

    Lots of wolf packs in the ghetto looking to over come.

  • flintman50 June 12, 2017, 8:40 am

    Guess it would be nice to have if you were being attacked by a wolf pack……

  • W.P. Zeller June 12, 2017, 7:55 am

    So, the X version is what the 320 should have been all along? Got the ergos straightened out and the other problems toned down?
    I suspect that IDPA (the weakest of the action shooting sports in this region) is not what they were going for- 3-gun is all the rage these days and that’s where the real sports money is. This looks a lot like a 3-gun pistol: giant gun, small caliber, enormous magazine.
    Hard to see any other use for it, even a .40-cal Limited version.

  • Andrew see May 31, 2017, 7:45 am

    Great gun, for sure. Great video here and reveiw covered all the points of this fine arm. Would love to see the Talo company’s take. Tried to find it no luck, got a link.?

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