Dirty Bird Brand AR-15 PartsCalifornia Compliant, Pistols
Sig P320-M17 and P320-M18: Not Your Average P320
Sep
When I recently made a trade at my local gun store for a Sig P320-M17, I thought what I was getting was a pretty much standard Sig P320, however once I dove deeper, I discovered that these pistols have some unique quirks that are well worth knowing about. While I love my 320-M17 now, there were some moments where I wish I would have done some more research beforehand.
320-17 and 320-M18 – An Introduction
When it comes to the Sig Sauer P320 family, the Sig P320-M17 and M18 variants stand out as the military’s chosen sidearms. But here at Dirty Bird Guns and Ammo, we’ve noticed that many civilian shooters don’t realize just how different these models are from their standard P320 counterparts. If you’re considering adding a Sig P320-M17 or M18 to your collection, it’s crucial to understand what makes these pistols unique – and potentially challenging for some users.
The M17 and M18 aren’t just P320s with a fancy paint job. These military-inspired handguns come with a set of features and quirks that can surprise even experienced P320 owners. From manual safeties that limit grip module compatibility to unique optics mounting solutions that might leave you without iron sights, the M17 and M18 require a bit more consideration before purchase.
In this article, we’ll break down the key differences, potential pitfalls, and special considerations you need to keep in mind when looking at the M17 and M18. Our goal is to ensure that when you walk out of our shop with one of these impressive firearms, you’re fully aware of what you’re getting – both the good and the potentially tricky.
Sig P320-M17 and P320-M18 – Military Spec vs. Civilian Models: Important Distinctions
Before we dive deeper, it’s crucial to understand that the Sig P320-M17 and P320-M18 available to civilians are not identical to the actual military M17 and M18 models. While they share many features, there are some key differences:
- The military versions have an anti-tampering mechanism that the civilian models lack.
- Military models use a different paint finish that’s more durable and corrosion-resistant.
- The true military versions have slightly different internal components optimized for duty use.
These differences might seem minor, but they have some important implications, especially when it comes to accessories and parts compatibility.
One notable example is the optics mounting system. The actual military M17 uses a unique optic cut that’s different from the civilian P320-M17. As a result, Sig’s expensive military-spec M17 optic cannot be used on the civilian version. This is a common point of confusion for many buyers, and it’s important to be aware of this limitation when considering optics for your P320-M17.
For civilian P320-M17 and M18 owners, this means you’ll be choosing from the standard P320 optics options, which we’ll discuss in detail later. While this might seem like a drawback, the good news is that there are still a few excellent optics available for the civilian models.
Sig P320-M17 & M18 – The Manual Safety Quirk
One of the most significant differences between the M17/M18 and standard P320 models is the inclusion of a manual thumb safety. For those of us who cut our teeth on 1911s and Browning Hi-Powers, this feature is a welcome addition, especially considering the P320’s lack of a trigger safety. However, it’s not without its drawbacks.
The manual safety limits compatibility with some aftermarket grip modules. While options like the Wilson Combat replacement grip do accommodate the safety, many others don’t. For the handy among us, some careful work with a Dremel tool can modify incompatible grips, but it’s certainly something to be aware of before making a purchase. If you were planning to swap out your P320-M17 or 18s grip module, it’s probably worth seeing if the one you want has a manual safety version, or is made of a material that is easily modified.
Optics Considerations
The M17 and M18 come optics-ready, which is fantastic for those looking to add a red dot sight. However, there are a few quirks to be aware of. First, removing the optics plate also removes the rear iron sights. This means you’ll either need to add replacement iron sights or choose an optic with built-in backup sights. As you shop for other P320s that are not M17 or M18s, you’ll see that many of these have a plate that is removed while leaving the rear sight intact. That’s not to say you wouldn’t need to swap out the factory sights with suppressor height sights, but at least there’s a place to put the replacement rear irons.
Secondly, and crucially, the M17 and M18 use the Delta Point Pro footprint, which is a bit of an oddball in the optics world. This limits your choices unless you’re willing to use adapter plates. While the Delta Point Pro footprint does offer some excellent optics options, it’s not as universally compatible as some other mounting standards, potentially restricting your choices or requiring additional accessories for mounting.
Optics Options: Enhancing Your M17/M18
When it comes to red dot sights for your M17 or M18, two options stand out in our experience: the Holosun SCS 320 and the Sig Romeo X series. These optics are particularly noteworthy because they’re designed to mount directly to the M17 and M18 without the need for adapter plates. This direct mounting capability not only provides a lower profile and more secure fit but also maintains the original design intention of the pistol. By avoiding the need for adapter plates, these optics help preserve the gun’s reliability and aesthetics while offering seamless integration with the M17 and M18’s Delta Point Pro footprint.
The first optic to consider has 320 in it’s name. The Holosun SCS 320 is a game-changer specifically designed for the P320 platform. This low-profile optic sits impressively close to the slide, offering a clean and streamlined look. What truly sets the SCS 320 apart is its innovative power source. Unlike traditional red dots, the SCS uses a combination of solar power and an internal battery. This unique system means you’ll never need to change batteries – a significant advantage for a defensive firearm. The optic charges itself using ambient light, and the internal battery serves as a backup for low-light conditions. We’ve found the auto-brightness feature adjusts flawlessly to ambient light conditions, ensuring a clear, visible dot in any environment.
The SCS 320 also offers multiple reticle options. You can choose between a 2 MOA dot, a 32 MOA circle, or a combination of both. This versatility allows shooters to select the reticle that best suits their needs and preferences. In our experience, the combination 2 MOA dot with 32 MOA circle tends to be the most popular among our customers, offering quick target acquisition for close-range defensive use while maintaining precision for longer shots.
One important caveat on the SCS 320: while it is made to fit the P320, t’s crucial to note that the SCS 320 does not co-witness with factory iron sights NOR does it have a rear notch iron sight built in. For us at Dirty Bird Guns and Ammo, this was actually a deal-breaker. We believe in the importance of backup iron sights, especially for a defensive firearm. This limitation led us to prefer the Sig Romeo X series for the M17 and M18. Your milage may vary on how important you feel the lack of rear irons is.
Sig’s own Romeo X Pro is also a top contender for the M17 (Romeo X Pro) and M18. Again, unlike the Holosun SCS, these optics are designed to integrate seamlessly with the P320 platform, offering a wide field of view and crisp, clear dots. What we particularly appreciate about the non-enclosed versions of the Romeo X series is the inclusion of built-in rear iron sights. This feature addresses the loss of rear sights when removing the original optics plate, providing a crucial backup sighting system.
The Romeo X series offers red dot options only. The Romeo X provides a 2 MOA dot with a 32 MOA circle option, which we believe is the best bet for most users. This combination provides rapid sight picture acquisition for close-range encounters while still allowing for precise shot placement at distance. The crisp red dot is highly visible in various lighting conditions, making it an excellent choice for both range use and defensive scenarios.
Sig has recently introduced enclosed versions of the Romeo series, which offer increased protection from the elements. However, we’re puzzled by their decision to omit the rear iron sights in these models. For us at Dirty Bird Guns and Ammo, this is a significant drawback. When it comes to a defensive handgun, we believe having backup iron sights is crucial. The lack of this feature in the enclosed models is, in our opinion, a deal-breaker for serious defensive use.
When choosing between these optics, consider your specific needs. If you prioritize never having to change batteries and don’t mind a solar-dependent system, the Holosun SCS 320 is hard to beat. If you prefer a more traditional battery-powered option with the security of built-in backup sights, the non-enclosed Sig Romeo X series is an excellent choice. Whichever you choose, both these options will significantly enhance the capabilities of your M17 or M18.
Finish: Form Over Function?
The coyote brown finish of the M17 and M18 is undeniably attractive, giving these pistols a distinct military aesthetic. However, we’ve noticed (and heard from customers) that this finish isn’t as durable as some might hope. Expect to see more scratches and wear than you might on other P320 variants. It’s the price you pay for that military authenticity, but it’s something to consider if you’re particular about keeping your firearms pristine. The pistol below has more than a few permanent blemishes after gentle treatment and less than 800 rounds downrange.
Sig P320-M17 – Accessories and Upgrades
Like its civilian siblings, the M17 and M18 benefit greatly from the P320’s modular design. The removable Fire Control Unit (FCU) allows for incredible customization, letting you switch frames, slides, and even calibers without dealing with additional firearm purchases.
For those looking to accessorize, we recommend considering a weapon light. The Streamlight TLR-1 HL and Surefire X300 both offer excellent performance and come in colors that complement the M17/M18’s aesthetic.
As for holsters, while the full-size Sig P320-M17 might be a bit large for comfortable inside-the-waistband carry, we’ve had great success with outside-the-waistband options like the T-Rex Arms Ironside.
Breaking In Your Sig P320-M17/M18
While Sig Sauer claims these pistols don’t require a break-in period, our experience suggests running at least 50 rounds through a new Sig P320-M17 or M18 can help smooth out any initial kinks. We recommend starting with slightly higher-powered 124-grain ammunition or even a few rounds of your chosen defensive ammo to ensure reliable function from the get-go.
If you experience any issues with the slide not locking back on an empty magazine, particularly with lighter 115-grain loads, don’t panic. This can often be resolved by using higher-grain ammunition or adjusting your grip to ensure you’re not inadvertently pressing the slide release.
Conclusion
The Sig P320 M17 and M18 offer civilian shooters a chance to own a piece of military-inspired hardware while enjoying the benefits of a modern, modular pistol platform. Their unique features, like the manual safety and military-style finish, set them apart from standard P320 models. While they may not be the perfect choice for everyone, for those who appreciate their distinct qualities, the M17 and M18 represent an exciting option in the world of modern handguns.
At Dirty Bird Guns and Ammo, we’re always excited to help our customers navigate the nuances of these military-inspired pistols. Whether you’re a collector, an enthusiast, or simply looking for a reliable self-defense tool, the M17 and M18 offer a compelling package that’s worth considering. Just remember to keep in mind the unique aspects we’ve discussed, from optics compatibility to finish durability, to ensure you’re making the right choice for your needs.
