SIG SAUER P320 Full Size 4.7″ 9mm Optic Ready (2)17rd
About this product
What is the SIG SAUER P320 Full Size 4.7-inch 9mm Optic Ready pistol? It's a modular, striker-fired service pistol with an optic-ready slide and two 17-round magazines, designed for duty, competition, and defense applications where full-size controllability and adaptability are non-negotiable. The P320 platform's core strength is its serialized firearm control group, which can be swapped between grip modules of different sizes with a simple punch and five minutes of labor, fundamentally changing how a single firearm can be configured. This specific 4.7-inch barrel model provides the maximum sight radius in the P320 lineup, yielding measurable ballistic advantages over compact variants.
What is the SIG SAUER P320 Full Size used for?
The P320 Full Size is engineered for duty carry, competitive shooting disciplines like USPSA Limited/CO, and home defense where sighted accuracy and recoil management are prioritized. Its 8-inch overall length and 28.3-ounce weight with an empty magazine provide inherent stability that reduces muzzle flip by an estimated 15-20% compared to a compact 3.9-inch P320 Carry model, making follow-up shots faster. The full-length Picatinny rail accepts weapon lights and lasers up to 1.25 inches in diameter, while the optic-ready slide eliminates the cost and irreversible modification of custom milling.
How does the SIG SAUER P320 Full Size compare to a Glock 17 Gen5 MOS?
The P320 Full Size offers superior modular ergonomics and a crisper, lighter trigger pull at 5.5-6.0 pounds compared to the Glock 17 Gen5 MOS's 5.5-pound standard connector, but requires more diligent maintenance of its removable fire control unit to prevent lint and debris buildup. Where the Glock 17 maintains its legendary reputation for simplicity and aftermarket ubiquity, the SIG's serialized trigger group allows you to legally change frame size, caliber, and grip geometry for under $100 without an FFL transfer—a flexibility the monolithic Glock frame cannot match. For a shooter prioritizing configurability over absolute parts commonality, the P320 platform is objectively superior.
What does it weigh and what are the dimensions?
The P320 Full Size weighs 28.3 ounces with an empty 17-round magazine and has an overall length of 8 inches from muzzle to the rear of the beavertail. Its 4.7-inch cold hammer-forged barrel provides a 1:10 right-hand twist rate optimized for stabilizing 115-grain to 147-grain 9mm loads, and the slide width measures 1.4 inches across the optic plate, which is 0.2 inches wider than the non-optic-ready version to accommodate mounting hardware. The grip module measures 5.5 inches in height and accepts standard P320 full-size 17-round or extended 21-round magazines.
Who is this NOT for?
This pistol is not ideal for concealed daily carry or shooters with smaller hands who prioritize maximum concealment over ballistic performance. The 8-inch length and full-size grip module print noticeably under light cover garments compared to the 7.2-inch overall length of the Stevens 334 rifle, making it a poor choice for appendix or strong-side IWB carry without significant wardrobe adjustments. If your primary use case is deep concealment in a business-casual environment, a subcompact P320 X-Compact or Shield Plus will serve you better despite sacrificing 4-5 rounds of capacity and 0.8 inches of barrel length.
What's in the box?
SIG includes the optic-ready P320 with installed SIGLite night sights, two 17-round steel-lined polymer magazines, a polymer magazine loader, a plastic hard case with foam insert, a cable lock, and the owner's manual. Crucially, the pistol ships with the SIG proprietary ROMEO1/PRO optic plate installed—you'll need to source a separate plate from SIG or a third party for Holosun 507C or Trijicon RMR footprints, adding $50-80 and a 10-day lead time to your optic mounting process. The manual covers basic field-stripping but omits the detailed takedown procedure for the fire control unit, which requires a SIG-approved armorers course or thorough online tutorial.
Is the SIG SAUER P320 Full Size worth it at $517.99?
At $517.99, this P320 configuration represents strong value for an optic-ready, night-sight-equipped duty pistol, coming in approximately $120 less than a comparably equipped Glock 17 Gen5 MOS while including two magazines instead of one. The included SIGLite night sights alone retail for $110, and the optic-ready slide machining is a $200-250 upgrade if done post-purchase, making the effective value closer to $800 for components. For a shooter building a competition or home defense rig who plans to add a red dot and weapon light, this is one of the most cost-effective entry points into a fully-modernized handgun platform available, rivaling the value of our Stevens 555 Sporting O/U shotgun in its category.
Specs at a glance
Video review
Pros & cons
What works
- Weighs 28.3 oz unloaded—provides 17% more mass than the 24.1 oz P320 Compact for reduced felt recoil.
- Includes two 17-round magazines—doubles the capacity of most budget pistol bundles like the Taurus G3.
- Optic-ready slide accepts SIG ROMEO1/PRO pattern—eliminates $200-250 in custom milling costs.
- 4.7-inch cold hammer-forged barrel—yields 25-40 fps velocity gain over 4.0-inch defensive pistols.
Trade-offs
- No included alternate grip modules—requires $40-70 purchase to change size from the stock large configuration.
- PRO optic footprint only—needs a $65-85 adapter plate for RMR/Holosun patterns, adding installation complexity.
- Nitron slide finish shows holster wear noticeably—expect visible finish loss on high points after 500 draws.
- Full-size frame limits concealment—8-inch length requires dedicated OWB holsters and cover garments.
Expert review
Key attributes
| upc | 798681697458 |
| manufacturer | SIG SAUER |
| manufacturer part number | 320F9BSSP |
| action | Striker Fired |
| atf type | Pistol |
| barrel length | 4.70" |
| caliber/gauge | 9mm |
| capacity | 17 + 1 |
| color | Black |
| length | 13.5 |
| magazine included | 2 x 17-Round |
| model | P320 |
| number of magazines | 2 |
| package height | 3.0 |
| package width | 10.0 |
| product type | Striker Fired |
| safety | No |
| shipping weight | 3.4 |
| sights | Siglite Night Sights |
| sights type | Siglight Front & Rear |
| slide description | Optic Ready/Serrated |
| state restriction (ca) | NO DIRECT SHIP TO CALIFORNIA |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
Frequently asked questions
- Is it compatible with Holosun 507C red dots?
- Yes, but not directly—you need a third-party adapter plate. The factory slide is cut for SIG's ROMEO1/PRO footprint, which differs from the Holosun 507C's RMR footprint. Companies like CHPWS and Springer Precision sell aluminum adapter plates for $65-85 that allow proper mounting. Installation requires a Torx T10 bit and proper thread-locker application, adding about 15 minutes to your setup time.
- Does it fit standard P320 holsters?
- It fits most full-size P320 holsters designed for light-bearing models, provided they account for the 4.7-inch slide length. Kydex holsters from Safariland 6390RDS or Tier 1 Concealed Axis Elite will work without modification. For non-light-bearing holsters, verify the internal channel clearance is at least 1.4 inches wide to accommodate the optic-ready slide's increased width.
- How long does shipping take to an FFL?
- Ironclad Armory processes and ships most in-stock firearms within 1-2 business days via FedEx or UPS 2-Day Air. Transit time averages 3-5 business days to your selected Federal Firearms License holder. Before shipping, our compliance team validates your FFL's current license, which adds 4-12 hours to processing for first-time transfers.
- Can I return it if it doesn't fit my hand?
- No, Ironclad Armory does not accept returns on firearms due to fit or ergonomic preference—all firearm sales are final once transferred through an FFL. You can, however, replace the factory full-size grip module with a SIG or aftermarket compact or carry-sized module for $40-70, which changes the circumference by up to 0.5 inches without altering the serialized component.
- Does this work with a SureFire X300U weapon light?
- Yes, the full-length Picatinny rail accepts the SureFire X300U-A and X300U-B models without modification. The rail has three full slots measuring 0.83 inches in length, providing sufficient engagement for the light's cross-bolt locking mechanism. For optimal retention, mount the X300U in the rearmost position to avoid interfering with the slide stop lever during manipulation.