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SIG Sauer P320 XTEN: Is A Bigger P320 Better?

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Some people say “bigger is better,” while others say “size doesn’t matter.” The truth is for you to decide, but in my book – magnum cartridges aren’t something I care about often. I’m pretty basic, .22 LR, 9mm, 5.56 NATO, and 6.5 Creedmoor are what I stack deep.

But when you need a bigger gun, nothing else will do. And in those cases, 10mm Auto is my pick.

SIG Sauer’s P320 XTEN gives you a 5-inch barrel, 15+1 capacity, and a pretty reasonable price of about $800.

Is it worth it? Does it work? And what do you do if your bears are cocaine addicts? This and more coming up. 


  • CALIBER: 10mm Auto
  • MAGS INCLUDED: (2) 15rd Steel Mag
  • SIGHTS: X-RAY3 Day/Night Sights
  • PISTOL SIZE: Full-Size
  • OVERALL LENGTH: 8.5 in [216mm]
  • OVERALL WIDTH: 1.3 in [33mm]
  • HEIGHT: 5.6 in [142 mm]
  • BARREL LENGTH: 5 in [127mm]
  • WEIGHT: 33 oz [936 g]
  • SIGHT RADIUS: 6.8 in [171mm]
  • TRIGGER TYPE: XSeries Straight
  • GRIP MODULE: Full-Size Polymer XSeries
  • GRIP MATERIAL: Polymer
  • GRIP COLOR: Black
  • BARREL MATERIAL: Carbon Steel
  • FCU MATERIAL: Stainless Steel
  • SLIDE FINISH : Nitron
  • SLIDE MATERIAL: Stainless Steel


If you’re wondering, “Is the Xten just a big P320” the answer is yes. But with that size come some minor modifications.

First off, while most of the trigger-related parts of the FCU are interchangeable between the XTEN and the standard P320, the FCU as a whole is only one way compatible. As in, the XTEN can drop into a normal P320 and run smaller calibers like 9mm and 357 SIG, but the smaller caliber FCUs cannot be used to fire 10mm or .45 ACP. 

The smaller caliber FCUs will drop into the XTEN frame, but the magazines won’t be able to seat.

Along those lines, the XTEN grip is almost exactly the same as the standard P320. The grip is the same thickness, but the inner diameter is larger for the larger 10mm magazines.

Overall I would recommend not trying to switch the XTEN back and forth with something smaller like 9mm; it’s a lot easier just to get a second P320 if you want to run things smaller than 10mm.

All that said, it’s remarkable how close the two feel and shoot. Besides the larger recoil and a heavier barrel with the 10mm, it’s honestly really hard to tell that the XTEN is not the same as the P320.


Maybe you just like the cartridge, maybe you want a caliber that not only stops a threat but sends a message while doing it, maybe you need to compensate for something, and a lifted F-150 is out of your budget. 10mm is an auto-loading magnum cartridge that packs a lot of punch, at least for an autoloader, but without getting into the crazy land of uncontrollability. 

9mm 124-grain HST, one of the most popular and proven 9mm self-defense options on the market, is a 124-grain bullet moving at about 1,150 FPS for about 364 ft.lbf of energy.

Compare that to a popular 10mm full power load like Buffalo Bore’s 220-grain hard cast lead moving at 1,175 FPS for a power-packed 675 ft.lbf of energy.

That’s a lot of boom right off the bat, but also bear in mind that most modern auto-loading 10mm pistols hold at least 15 rounds per magazine. Now that’s some firepower.

For me, a 10mm auto-loader has been high on my list as a bear gun. By “bear gun,” I don’t specifically mean just bears, simply that my primary threat is four-legged, not two. Bears, mountain lions, chupacabras, oh my.

I like the SIG P320 platform, so when the XTEN was introduced, it seemed like a good fit for me. Having recently moved to a state where I can finally get the XTEN, I picked one up literally the same day I got my new state ID.


I’m not sure I own a single factory firearm, I have a compulsion to tinker. But my XTEN is closer to stock than most of what I own. For the first 200 rounds, I left the gun totally stock to get a good feel for what I wanted to change. Well, not totally – I added a SIG Romeo 2. SIG Sauer claims that the Romeo 2 is one of the few red dots on the market that can handle the 10mm recoil, so I’ll put that to the test.

By the end I didn’t find anything that needed to change. The factory XTEN is a full-size P320 that is practically the same size as the normal full-size P320, just a few ounces heavier and shooting a much bigger cartridge.

First day out, I ran about 100 rounds of S&B 180-grain FMJ at about 1,150 FPS. Zero issues, zero malfunctions, nothing but smooth firing. This was my main range ammo, good for practice but not what I would carry.

The very first 15 rounds through the SIG XTEN. 10 yards, 6 MOA dot that wasn't zeroed yet. The circle is 3″

Once the first 100 were down, I felt like the gun should be broken in, and I got into some more spicy loads. First up, Hornady 155-grain Hollow Point XTP. These were clocking in at 1,400 FPS and had some real zip to them. Another 100 rounds, no issues.

Big thanks to and Hornady for providing these!

Now for the spicy stuff. Buffalo Bore 220g-grain Hard Cast at 1,170 FPS. These are some big boy rounds, and you can feel it in your chest when you light one-off. Since these are also kind of really expensive, I only put down 40 of them. But still, zero issues.

240 rounds of 10mm, and everything works perfectly. Not a single failure to anything, no jam, no nothing. And the Romeo 2 kept on kicking.

After 240 rounds, I felt the need to tinker a little. But there isn’t much I feel the need to change on the XTEN. The trigger pull is the standard P320 X series trigger, pretty good by striker standards but not amazing. While normally I would be all for swapping out springs and making it lighter, I actually want to keep it as is since this will be a field gun. Something about the increased abuse and unpredictability of the outdoors makes me appreciate the extra margin of safety.

To add to that, I did change out the trigger shoe for the Agency Arms P320 trigger. The standard trigger is a nice flat X series trigger, but the Agency Arms trigger includes a trigger safety like you would find on a Glock.

Agency Arms P320 trigger

I don’t think this is necessary on most P320s, but for the reasons above, I thought, why not.

Another 200 rounds later, and I still have no complaints. The trigger works flawlessly, the gun works every time, and I’ve had zero issues.


One of the pretty clear downsides of the XTEN is that holster options aren’t great right now. There are a few out there, but not a ton. Because the dimensions are just slightly different from the normal P320, normal P320 holsters are hit-and-miss for compatibility. I get the heebie-jeebies about trying to force a pistol to fit a holster that wasn’t made for it, so that’s a hard pass for me.

Since I plan on carrying this in the field, either hiking or hunting, I wanted something flexible so that I can change how I carry. The Blackhawk Omnivore holster is what I landed on to try out.

Blackhawk Omnivore

Blackhawk was nice enough to send this holster out for testing, and testing is going well so far. While the holster works with over 150 different firearms, the firearm needs either a light or a rail for it to lock into the Omnivore. For this application, I went with the no-light version. And since it doesn’t have a light on it, the Omnivore makes you add a little locking bar to the railing of the dust cover so it can lock into the holster.

Not something I’ve had to do before for a holster, but I like the system. It might look a little strange to have a piece of plastic attached to the rail, but it lets me use multiple pistols with one holster and thus adding to the flexibility of my little system.

While great for open carry in the field, I wanted an option of something slightly more low profile also. 5.11 sent one of their Skyweight Utility Chest packs out a few months ago, and now was the time to put it to use.

The larger of the two Skyweight chest rigs they offer, this one has a ton of room in it. Not only can I fit and conceal the XTEN (including the rather large Romeo 2 on top), but I still have room for a full IFAK plus room to spare for whatever else I might want to take with me.

For a casual day hike where I want to keep chapstick, bug spray, and meat sticks close to hand but also be able to carry the XTEN without scaring the suburbanites I might pass on the trail – this is a pretty great setup.

I even still have room to carry an extra magazine. You know, just in case the bears have power armor. 


10mm is a fun cartridge. Not only is it a big boom with lots of ammo in the mag, but it also has a ton of options for loadings.

Most 10mm is on the weaker side. Anything in the 180-grain-ish range moving at 1,150 FPS or less is considered a weak load for 10mm. While these are still a lot more power than even warm 9mm, it’s not taking advantage of the caliber.

If you want the spicy stuff, Underwood and Buffalo Bore are your best bets. Hornady has some good two-legged ammo choices, but they expand too much and don’t offer the penetration that you might want if you’re facing down a bear on cocaine. 

I would like to mention a huge thanks to and Hornady. Hornady provided their ammo, and AmmoToGo provided the rest of the ammo for this review.


This is one of the rare reviews where I have no complaints. I have nothing negative to say about any part of what I tested. This feels weird to me, but here we are.

My SIG XTEN worked 100 percent from start to finish. Spicy ammo, range ammo, it didn’t matter. I’ve read a lot of people have had problems breaking in their magazines to get all 15 rounds of 10mm to fit, but I loaded all 15 in both mags from the start.

Accuracy with the XTEN is great, reliability has been perfect, and even as a 10mm novice, I don’t feel like the recoil was a real issue at all.

The recoil is spicy but totally manageable, with good fundamentals. 

I deeply hope never to need to deploy my bear gun against anything living, but I feel extremely confident with this system should the need arise. 

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1 Comment

  • Robert Nierenberg says:

    Great Review of terrific Fire Arm. What makes it even better is much easier to handle with Gas Pedal thumb Assist

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  • Great Review of terrific Fire Arm. What makes it even better is much easier to handle with Gas Pedal thumb Assist

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