One of the most popular guns right now is the Sig P320, and for good reason. The armed forces announced the Sig P320 would be its next official sidearm and the gun started flying off store shelves.
Granted, it has a lot going for it anyhow, so it’s not like there wasn’t any reason to buy one before that happened.
That said, it is likely to remain a wildly popular pistol for years to come. If you might wonder why, here is just about everything you need to know about the Sig Sauer P320.
The Sig P320 is, in and of itself, an evolution from the Sig P250 pistol design. The Sig P250, just like the 320, is/was modular in that most of the firing mechanism – the trigger, sear, slide release and ejector/extractor mechanism – can be swapped in and out of any compatible frame.
This gives you the option to install the trigger in a full-size, compact or even subcompact gun or – if so desired – even swap calibers. The trigger group – which Sig Sauer calls the Fire Control Unit – is pinned into the frame via the axis pin of the slide release lever. Take that out and customize at will.
The Fire Control Unit is what the federal government deems to be the “firearm” in and of itself, as the gun would be incapable of firing otherwise. As a result, the fire control unit in the Sig P320, just like the P250 before it, has the serial number of the firearm printed on it.
While most appreciated the modularity, not everyone appreciated the P250 when it came to actually shooting the thing. The P250, you see, is/was a hammer-fired light double action only gun. Were you to compare the two fire control units side by side, you’d notice the hammer at the rear of the P250’s trigger group.
The P320, however, is striker-fired, so the fire control unit has the firing pin release instead of a hammer.
A double-action mechanism isn’t necessarily synonymous with a hard trigger pull; pull weight is due to the tension of the trigger springs. This can be reduced by employing a shorter spring. For instance, a very old trick for tuning Smith and Wesson revolvers was to clip one turn of the trigger spring to lighten and smooth the pull. The P250 only had about a 6-lb pull, so it was hardly unmanageable.
Instead, it was the relative length of the trigger pull. After all, double-action pistols cock the hammer with the trigger pull, then drop the hammer and engage the firing pin.
Since the modern shooter tends to prefer a striker trigger over a single-action or double-action trigger due to the shorter, lighter trigger pull (and because that’s what most gun companies make) that means the P250 didn’t entirely fit the market.
That led to the P320 being developed and the P250 being slowly discontinued. Until recently, you could get one or the other, but the P250 is – like the snows of yesteryear – gone from Sig Sauer’s catalog.
The Sig P320 Grip Module System
So, now that you understand the Sig P320 firing system, next is understanding the Sig P320 grip module scheme.
It’s all relatively straight-forward; the trigger module drops into any frame size you want. There are four choices as to size. In descending order, they are Full-Size, Carry, Compact and Subcompact. Sig also offers X-series frames, which have different grip stipling, a longer beavertail and a trigger guard undercut for improved ergonomics, in Full-Size and Compact sizes.
Think of the X series sort of like GMC trucks compared to Chevrolet; underneath, they’re exactly the same. It’s just one gets a slightly different body kit and badge on the grille.
Additionally, there are Small, Medium and Large grip sizes available for each frame size. This changes the palm swell as well as the distance between the rear of the grip and the trigger. This way, the pistol can be tailored to your ergonomic need.
The Full-Size frame, naturally, is for the full-length slide, 4.7-inch barrel and magazines. Barrel length is 4.7 inches, and the pistol’s overall dimensions are 8 inches long, 5.5 inches tall and 1.3 inches wide. The magazine holds 17 rounds of 9mm, 14 rounds of .40 S&W or 10 rounds of .45 ACP depending on the caliber you choose.
The Carry and Compact frames both utilize a compact slide and barrel, but the Carry frame has a longer grip to accommodate full length magazines. Barrel length is reduced to 3.9 inches – though a 4.6-inch threaded barrel is available for those who want one- – and overall dimensions to 7.2 inches long, 5.3 inches tall and 1.3 inches wide. The Carry model is 5.5 inches tall, however. The Compact’s capacity is reduced to 15 rounds of 9mm, 13 of .40 (or .357 Sig) and 10 rounds of .45 ACP, but the Carry model remains the same.
Both the Carry and Compact frames can also accommodate a Full-Size slide if so desired.
The Subcompact reduces barrel length to 3.6 inches, and overall dimensions to 6.7 inches long, 4.7 inches tall and 1.3 inches wide. The standard magazine holds 12 rounds of 9mm or 10 of .40 S&W.
Caliber X-Change For Sig P320
Since the trigger group can be swapped between frames and therefore calibers, caliber conversions are made very easy – you just need to buy a Caliber X-Change kit from Sig Sauer. Essentially, each kit is a complete pistol less the fire control unit. You just drop in the trigger group.
Grip modules are also available. If you wanted to just switch between grip module sizes with only one slide, all you’d need is the grip module and magazines.
Caliber X-Change kits come with the slide (with firing pin/striker assembly installed) and the barrel, recoil springs and the grip module. You just drop the trigger group in the frame and presto! Shoot 9mm or .45 ACP with a quick swap, and go back again with ease.
Just like the P250, that’s part of the appeal. If you decide you’d like to carry a .45 ACP or just shoot both at the range, you totally can and don’t have to pay for a whole new gun. Caliber X-Change kits run you $407, which isn’t exactly bargain-basement but still much less than buying a whole new P320.
The XM17 Modular Handgun System Trials
That said, what made this gun’s name is that it was selected to be the next official sidearm of the US armed forces as the winning entrant of the M17 handgun trials.
Stocks of the previous standard issue pistol, the Beretta 92FS/M9, were starting to show their age. The M9 also had some issues functioning in desert environments (mostly due to the magazines) and while Beretta had – to their credit – done plenty to address some of the concerns, a new gun was wanted.
Specifically, what was wanted in a new pistol was modularity, so it could fit multiple hand sizes. The M9, after all, is a brick and folks with smaller hands have a hard time getting a good grip on one. For plainclothes operations, they also wanted a pistol that could be concealed. It also had to have ambidextrous controls, and the ability to be fitted with optics (RMR) if so desired.
Obviously it had to pass reliability tests (including desert conditions) and had to have a price that was nice, since – make no mistake – cost is definitely part of bidding for government contracts.
Ultimately, the Sig Sauer XM17 pistol – which does differ from the P320 in some aspects, such as ambidextrous manual safeties – was the winning entrant. It passed the reliability and safety tests, was definitely accurate enough for government work and – again, it was a factor – had the virtue of being one of the lowest-cost entrants.
Glock, for instance, offered the 19X pistol…for $100 million more than Sig Sauer was offering for the same number of P320 pistols.
If you want to give a pistol pedigree, get an army to buy it. Ask the 1911 guys sometime, they’ll tell you all about the two World Wars. The Browning Hi Power fans will likewise chime in about how the Brits, Canadians and so on carried the BHP…you get the general idea.
Anyhow, the news broke and P320 pistols started flying off store shelves.
The M17 vs Sig P320
What are the differences between the M17 and Sig P320? After all, if I’m not getting the military gun, what sets it apart from the one I can buy at Cabelas or my LGS?
Good thing to ask! Nothing that’s singularly enormous, but a few moderate changes that do add up.
The standard M17 comes with a 21-round extended magazines and a 17-round flush fit box. The Full-Size P320 comes with two 17-rounders. The M17 uses the Carry frame (for full-size magazines) but has a full-size slide and barrel. It does have a M1913 rail, but the difference is that the Full-Size P320 has a full-length dust cover.
The M17 has ambidextrous manual safeties mounted on the frame, much like many 1911 pistols these days. The standard P320 is Sig Sauer’s Nitron finish; the M17 has a Coyote tan PVD finish.
The M17 has a removable rear sight plate, which allows the user to easily install a rear optic. The standard P320 does not. Instead, the standard P320 wears SIGLITE night sights or white dots. SIGLITE sights are standard on the M17 as well, but obviously the M17 does have the removable plate.
There were a few other improvements (a loaded chamber indicator, tighter seal around the trigger to keep sand and other detritus out of the gun) but the above were some of the key points.
The good news is you can get both; Sig Sauer made a limited run of 5,000 M-17 Commemorative pistol kits, which are literally the same as what Sig sent to the 101st Airborne, some of which are still available for purchase. Or you can buy the M17 as they package it for civilians, which includes only 17-round magazines, and can be had in Nitron or Coyote Tan.
The M17 for civilians differs only in that it ships with carbon steel control pieces and 17-round magazines only; other than that it’s the same gun. The M17 Commemorative appears to have a slightly darker shade of tan, but other than that there isn’t much difference.
Is that enough to justify paying $1100 for the special edition as opposed to $770 for the standard M17 model? You’ll have to be the judge, but you don’t really get anything extra besides an extended magazine and a cardboard box case.
Sig Sauer M18
The M18 is supposed to be a “compact” version of the M17…but using that word to describe it doesn’t seem right. One does not think it means what other people think it means.
The Sig M18 has a shorter frame dust cover, slide and barrel than the M17 but the grip is the same length; in essence the P320 Carry model, with the same 4-inch barrel, just in FDE rather than black. So not really a compact.
The M18, however, was selected as the service pistol for the US Air Force, US Marine Corps and US Coast Guard. There’s also been some discussion about use by certain special personnel in concealed carry roles, but who knows if that’s true or not.
Sig P320 X, RX and Tacops Pistols
Ah, but what if you aren’t content with basic black anymore? You need a tactical wundergun, and for that the Sig P320 X series, along with the RX and Tacops series are perfectly suited. These pistols feature refinements that the standard series does not, tailor made for certain sensibilities.
Just like the diversity of choice among other guns such as Colt 1911 pistols and so on, almost anyone can find a Sig P320 for their intended use.
The Sig P320 X pistols have a different grip frame, featuring different stipling, extended beavertails, a trigger guard undercut and revised controls. The magazine well is flared and beveled for easier reloads and the slide is ported to make the pistol a little less nose heavy. The X-Carry has Sig’s X RAY night sights, though the rear sight is on a removable plate if an optic is desired. The X-Five Full-Size has a rear target sight, also on a removable plate.
The X-VTAC puts a full-size Coyote Tan slide on the black X-Carry frame, with Sig Sauer’s Viking Tactical sights (the VTAC). It does not have the removable rear sight plate, however. All Sig P320 X pistols also feature a straight-blade trigger, rather than the more traditional curved trigger of the standard series.
The P320 TACOPS Carry is the suppressor-ready pistol of the P320 line, with an extended threaded barrel and suppressor sights. Otherwise, it’s the same as the standard P320 line.
Then you have the P320 RX series, in Full-Size and Compact frames. The RX series come with Sig Sauer’s ROMEO1 3 MOA red dot optic installed, along with either SIGLITE or tall contrast sights – your choice – straight from the factory.
If you need something a little more serious than the standard gun…these are the models to have.
The Sig P320 Safety System
By now, you’ve either heard of or are wondering about the Sig P320 safety system, especially since there was the scare involving drop fires.
The issue was found when the Sig P320 was dropped at a specific angle and if equipped with the non-tabbed trigger, which featured a tabbed trigger safety much like other striker-fired pistols. Granted, drop fires or a potential drop-fire with any gun is a bad thing, so it was definitely not making a mountain out of a molehill.
Sig Sauer had a soft recall and offered a free upgrade to anyone asking for it. They installed the tabbed trigger for owners and revised the non-tabbed trigger to fix the issue.
The tabbed trigger adds a passive trigger safety, meaning the trigger cannot be pulled until the tab is pressed, just like with a Glock pistol. Besides this feature, the standard curved trigger has a firing pin block safety and a disconnect from the sear.
At rest, the trigger group cannot release the striker, which is pre-cocked by cycling the slide. Additionally, a firing pin block locks the firing pin in place, preventing it from moving even if the sear were somehow tripped. This ensures a safe carry in case the pistol is dropped.
It bears mentioning, however, that no pistol is 100 percent drop-safe. There is a failure rate to any and every mechanical system; given the right conditions any gun can be made to discharge accidentally. The only way to ensure no drop fires ever happen no matter what conditions exist on any pistol anywhere is to not load it.
The issue with the Sig P320 was not anticipated by the manufacturer, despite Sig Sauer – one of the largest handgun manufacturers on the planet – having taken pains to ensure that the P320 pistol was a safe design. That said, the issue was discovered after release (which happens) and steps were taken to correct it.
Which P320 Pistol Should I Get?
The beauty of the Sig P320 pistol is that it’s modular, so there’s a model that can appeal to just about anyone. Well…there are some folks that will get left out. If you only like revolvers, there probably isn’t a Sig P320 for you, but then you wouldn’t be looking at the Sig P320; you’d be looking at maybe a .38 Special revolver.
That said, it really depends on what you’re looking for in a pistol.
For concealed carry, the Compact and Subcompact pistols are the best options. The Carry models are good picks as well, though some people find the grip a little on the long side for daily CCW.
If carrying inside the waistband, some people might even consider mating a Full-Size slide to a Compact frame. This gives the pistol a longer sight radius and thus better accuracy but also – and this is something to note – helps tame felt recoil.
Felt recoil, you see, is influenced a great deal by the torque on the wrist which is itself influenced by the bore axis, or the distance between where the gun fits into your hand and the barrel. (This is why a high, tight shooting grip is recommended.) A pistol would be driven straight backwards if it went off in a vacuum. However, since it’s held in place by the hand, shooting it causes the pistol to rotate back and up.
The higher the bore axis, the greater the torque. Since Sig Sauers have a particularly high bore axis, even the big, heavy Sigs tend to feel a little snappier than guns of comparable weight and dimensions with a lower bore axis. The Sig P320 is no exception.
Granted, most people buy their P320 in 9mm and it isn’t like shooting even the P320 Subcompact will be like firing a .357 Magnum snubbie revolver. (Which hurts. A lot.) However, some folks might find it a little less enjoyable than some other guns like a Glock 19, CZ 75 Compact or M&P9C.
The full-size guns, of course, make wonderful home defense pistols or range guns. For competitive shooting, any of the X series guns would be absolute slam dunks, as the stock versions will run well and they can be upgraded with optics and whatever else you could imagine.
The Carry and Compact models are effectively Do It All guns, as the compact size makes them a good fit as carry pistols as well as being more than adequate to run as competition guns.
The Sig P320 would not, however, the best choice for handgun hunting. While the .357 Sig round touches the .357 Magnum’s 125-grain loading, 10mm is the better starting point for handgun hunting with a semi-auto. Sig Sauer currently does make some 10mm pistols, but none in the P320 series.
Or, if you prefer, you could get multiple frame, slide and caliber groups and carry the exact gun and caliber you want when you want. A modular system allows you to do that, which is incredibly convenient.