Duty Magazines by Role: Glock 15 and 17, P320 30, FN 509 20

Our earlier article argued the theory of OEM versus aftermarket. This one puts four real magazines on the table and assigns each a job.

Four magazines, four jobs

The standard advice about duty magazines is to carry factory ones and not to overthink it. That is good advice, and the longer treatment is in our OEM versus aftermarket guide. What that guide cannot do is tell you what to put in which pouch. This one tries.

Here are four specific magazines, and the honest role of each.

The belt magazines: factory 15 and 17

The Glock factory 15-round Gen5 magazine is listed for the Glock 19 and 26. The factory 17-round Gen5 magazine is listed for the Glock 17 and 34. These are the baseline: the pistol was built around them, they are the part agencies most often approve, and the ecosystem of pouches is designed for them.

Some practical points:

• A 17 in a 19. The G19 accepts the longer magazine. It extends below the grip, which gives you more rounds and a place for the pinky, and some users like that. The downside is that it can print under clothing and sits differently in pouches. Whether it is allowed is a policy question.
• Be consistent. If you carry both lengths, number them and keep them in a consistent order so the reload feels the same every time.
• Generations. Gen5 magazines are specified for Gen5 pistols. Compatibility with other generations is not automatic, so check before mixing.
• Pouches. A pouch sized for a 15-round magazine may not accept a 17. Match pouches to what you carry.

The range magazine: Sig P320 30-round

The Sig P320 30-round extended magazine is a steel magazine listed in a coyote color. Thirty rounds of 9mm in a pistol magazine is a lot of ammunition and a lot of magazine, and on a duty belt it becomes a problem: it extends well below the grip, it will not fit standard pouches, and it changes the handling of the pistol. As a range or training tool, it makes sense, particularly for drills that benefit from long strings without reloading.

Two cautions:

1. Capacity law. Some jurisdictions limit magazine capacity, and exemptions for law enforcement vary. Check before you buy or carry one.
2. Not a duty mag. Unless your agency specifically approves it and you have trained with it extensively, treat it as a range item.

The aftermarket magazine: ProMag 20-round for FN 509

The ProMag 20-round steel magazine is listed as an aftermarket magazine for the FN 509. FN's own listings for the 509 Tactical describe 17-round and 24-round magazines, so the 20 is a third-party capacity. We have written before about the FN 509 Tactical, and about the cautions that apply to aftermarket magazines generally.

ProMag is a well-known aftermarket brand. We do not have verified reliability data for this model and are not going to characterize it. What we can say:

• Verify fit and feed with your own pistol. Any aftermarket magazine should earn its place through function checks before it is trusted.
• Check agency policy. Many agencies require factory magazines for duty.
• Keep it separate. Mark aftermarket magazines clearly so they do not get mixed with approved ones.

If you want to carry more than 17 rounds in a 509, FN's own 24-round magazine is the factory choice.

How to test any new magazine

Before a magazine goes on a belt, give it a function check:

1. Number it. A permanent mark lets you track problems to one magazine.
2. Inspect it. Look for cracks in the feed lips, a bent spring or a loose baseplate.
3. Run it with your duty ammunition. Fire a meaningful quantity, including reloads.
4. Check lock-back. The slide should lock open on the last round every time.
5. Retire it if it fails. A magazine that causes a malfunction you cannot attribute to something else is not a duty magazine.

Safe handling comes first: do this at a range, under supervision if you are new to it, with the pistol pointed downrange.

Roles at a glance

Bottom line

Match the magazine to the job: factory for the belt, extended for the range, and aftermarket only after it has proved itself and your agency allows it. Verify compatibility with the maker, check local capacity law, and keep a numbered inventory. See the duty belt setup guide for how magazines fit into the layout.

Editorial note: This is an independent editorial overview built from manufacturer specifications and publicly available information. We have not performed hands-on testing of the products discussed, and nothing here is a performance guarantee. Verify specifications, compatibility and legality for your own situation.

Affiliate disclosure: Some links on this page are affiliate links to Ammunition Depot. We may earn a commission if you buy through them, at no extra cost to you. Our editorial choices are not influenced by commissions. Check current price, stock and specifications directly with the retailer.