SIG P320 & P365 Magazine Guide

TakTactical Buyer's Guide · SIG SAUER

SIG P320 & P365 Magazine Guide: Every Variant, Every Capacity, Every Use Case

The complete buyer's reference for SIG's two modular pistol families. In-stock at TakTactical, ships in 1-2 business days from our US warehouse.

Why This Guide Exists

SIG SAUER builds the two most popular modern pistol platforms in America right now: the full-size P320 (the M17/M18 service pistol family) and the compact P365 (the highest-selling concealed-carry pistol in the country). Both are modular. Both have a confusing number of variants — Compact, XL, X-Carry, X-Macro, Spectre, Legion, AXG — and each variant has its own magazine fit window.

If you buy the wrong mag, it either won't seat or will sit half an inch proud of the magwell. This guide breaks down which magazine fits which pistol, what capacity options exist, and which configurations are worth your money. Every product mentioned is in stock at TakTactical.

Part 1: SIG P365 — The Carry Pistol Family

The P365 launched in 2018 and changed the concealed-carry market overnight. It packs 10-12 rounds of 9mm into a frame thinner than most single-stack subcompacts. Since then, SIG has released a family of variants — each one a different compromise between concealment, grip length, and capacity. Pick the magazine to match the pistol you carry, not the one you wish you carried.

P365 Standard / P365 SAS (9mm, 10-12 round)

The original. Tiny, light, completely concealable. Standard capacity is 10 rounds flush or 12 rounds with an extended floorplate. The SIG P365 9mm 12RD Magazine is the go-to upgrade — same footprint as the flush 10-round but with two extra rounds plus a slight pinky rest for shooters with larger hands. We stock the black version with 94+ units in inventory, so same-day shipping is reliable.

For absolute maximum concealment when you don't need the extra capacity, the P365 9mm Subcompact 10RD Finger Extension (Coyote) gives you a 10-round flush mag with a subtle finger rest — better grip, no added length. Coyote finish for the shooter who doesn't want every accessory to match their black gun.

Spare mag in a different color? The SIG P365 12RD Coyote is the same 12-round capacity in coyote finish.

P365 X-Macro (9mm, 10-17 round)

The X-Macro is the answer to "what if I want a P365 grip with double-stack capacity?" Bigger frame, longer grip, optic-ready slide standard. The trade-off is concealment — it's noticeably thicker than the standard P365. But for IWB carry with an undershirt or appendix carry, it's the most capacity you can get in a single-stack-feeling pistol.

The SIG P365 X-Macro 9mm 10RD (Black) is the restricted-state-friendly capacity. Standard X-Macro mags ship at 17 rounds in non-restricted states. If you're in CA, NJ, CT, MA, NY, or any state with a 10-round limit, this is the magazine you need.

P365-380 (.380 ACP, 10 round)

The newest variant in the P365 family. SIG took the P365 frame and chambered it in .380 ACP for shooters who can't handle 9mm recoil — recovering from injury, smaller-framed shooters, or anyone who wants a lighter-recoiling pistol that still concealables.

You have two magazine options depending on your grip preference:

• P365 .380 ACP 10RD Flush — maximum concealment, flush baseplate. Best for pocket carry or smaller hands.
• P365 .380 ACP 10RD Finger Extension — adds a finger rest for improved grip. Recommended if you're shooting from a pistol with the longer grip.

Both are 10-round capacity — that's the standard for the .380 P365.

Part 2: SIG P320 — The Modular Service Pistol

The P320 won the U.S. Army's Modular Handgun System (MHS) competition in 2017, replacing the Beretta M9 as the standard issue sidearm (designated M17 full-size and M18 carry). Civilian P320 variants share the same fire control unit (FCU) as the military models, which means one FCU can be moved between Full, Compact, Subcompact, and X-variant grip modules. The magazine you need depends on which grip module you're running.

P320 Compact / X-Compact (9mm, 15 round)

The most popular daily-carry P320 variant. Compact slide, compact grip module, but full-size magwell that accepts double-stack magazines. The SIG P250/P320 9mm Compact 15RD Magazine is the standard capacity — 15 rounds of 9mm in a Compact-sized grip is exceptional concealed-carry performance.

The "P250/P320" designation isn't a typo: SIG's P250 (the predecessor to the P320) used the exact same magazine. If you're buying spare mags for a Compact P320, this is the one. We carry 56+ units in stock for fast shipping.

P320 Full Size (9mm, 10 round restricted)

The full-size P320 — same chassis as the military M17 — uses a larger 17-round magazine in standard configurations. For shooters in capacity-restricted states, the SIG P320 9mm Full Size 10RD (Coyote) is the option. Half-height magazine, full-frame grip — perfect for range work in restricted states or for a bench-rest position where a 17-round mag would interfere.

Coyote finish matches the military M17 aesthetic and looks correct on a coyote-frame X-Five Legion or M17 commemorative.

Part 3: Magazine Compatibility Chart

This is the question we get more than any other: "Will this magazine fit my pistol?" Here's the short answer. Cross-compatibility within a family (e.g., a P365 mag in a P365 SAS) is reliable. Cross-compatibility between families (a P320 mag in a P365) is impossible — different frame, different magwell, different geometry.

Key rule: P365 magazines do NOT fit P320 pistols, and vice versa. The two families share branding and a similar look but are completely different magazine architectures.

Part 4: How Many Magazines Should You Own?

For a carry pistol the minimum is three: one in the gun, two on the body or in a carry-ready stash. We recommend five for any pistol you actually carry — daily handling wears magazine springs, and rotating mags every few months extends their life. At $30-45 per magazine, this is a $150-225 investment for a lifetime of reliable feeding.

For range or competition use, more is better. Eight to ten magazines lets you load all of them at the bench, run a long string, then re-load while the lane runs cold.

Part 5: P365 & P320 Slide and Optic-Cut Conversions

Once you've sorted magazines, the next upgrade is an optic-ready slide. SIG ships the X-series and most current production with optic cuts standard, but if you have an older non-optic P365 the aftermarket has solid options.

• Lone Wolf Dawn Slide for P365 (Gunmetal Grey) — also available in Bronze and FDE. Drop-in slide with stippled grip texture and RMS optic cut. Direct upgrade from the factory slide.
• True Precision P365 Slide with RMS Cut (Grey) — premium aftermarket option. RMS direct-mount footprint fits Shield RMSc, Holosun 507K, and most modern micro red dots.
• Tyrant CNC P365 Slide Cap (Black) — small upgrade for shooters keeping the factory slide but who want a cleaner rear sight area.
• Tyrant CNC P365 Extended Slide Catch — drop-in slide release with extended thumb pad. Faster manipulation under stress.

Part 6: Holsters That Actually Work

A magazine without a holster to carry the loaded pistol is a paperweight. Two brands consistently fit the P365 family well — Mission First Tactical (MFT) for hybrid Kydex builds and Alien Gear Holsters (AGH) for adjustable retention. We stock variants for every major P365 configuration.

For the Standard P365

• MFT Hybrid Holster — SIG P365 — leather-backed Kydex shell, adjustable cant and retention, breathable backing for all-day IWB wear.
• Alien Gear Photon Holster — P365 with Weapon Light — for shooters running a TLR-6 or similar micro light on their P365.

For P365 XL / X-Carry

• MFT Hybrid — P365 XL (Black) · also Brown — same MFT hybrid construction, sized for the longer XL slide.

For P365 X-Macro

• MFT Pro Holster — P365 X-Macro · also P365 Black — Pro series with adjustable belt-clip cant for the wider X-Macro frame.

FAQ

Need Help Picking?

If you're between variants, between magazine capacities, or trying to figure out if a specific slide cut will work with the optic you already own — contact us. We carry SIG product daily, ship it daily, and answer questions from real humans.