Spare Mags for the Nightstand: PMAG GL9 and Window PMAGs

A spare magazine only helps if you know it works. Here is how to choose, label, rotate and lock up the ones you keep ready.

Spare magazines are a system, not an accessory

If your bedside gun has a magazine in it and nothing else, you have a plan for one malfunction-free event. A spare is a simple way to extend that, and the best way to use a spare is to know that it works, that you can find it in the dark and that nobody else can reach it.

This page looks at two examples from the catalog, a pistol magazine and a rifle magazine, and uses them to talk about the habits that matter.

The pistol magazine: PMAG 21 GL9

The Magpul PMAG 21 GL9 is a 21-round polymer magazine in the Glock pattern. It would be a candidate spare for a Glock-compatible pistol, and also for a carbine that accepts Glock-pattern magazines, such as some pistol-caliber carbines with interchangeable magazine wells. Our Henry Homesteader and PCC guide discuss that pairing.

Two cautions:

• Fit varies. "Glock-pattern" does not tell you every model, generation or frame length is a fit. Check the maker's compatibility list for your pistol.
• Longer magazines change how a pistol sits. A magazine that extends below the grip changes how the gun feels and may affect how it fits in a lock box or holster. Check, and practice with it.

The rifle magazine: PMAG Gen M3 Window 30

The Magpul PMAG Gen M3 Window 30 is a 30-round polymer AR-pattern magazine with a window along the side so you can see how many rounds are loaded. That is useful for inspection: you can tell at a glance if a magazine is empty or partially loaded. It is not a substitute for checking the firearm; verifying a chamber is a separate step.

For a home-defense AR, a spare magazine is a backup for stoppage or a longer event. Our home-defense AR setup guide lists the rest of the kit. Keep your spares in the same place and in the same orientation so you can find them in the dark.

The loaded-magazine spring myth

Among the oldest arguments in gun forums is whether you should leave magazines loaded. The folklore says a loaded magazine spring will "take a set" and weaken, so you should rotate magazines or leave them partly loaded. Here is the more careful version.

• A widely held view among magazine makers and many instructors is that springs wear mainly from repeated cycling, which means compressing and releasing, rather than from sitting compressed. Quality springs are designed to stay compressed.
• That view is not universal, and spring quality, age and design vary. We do not have a test result to quote and we will not invent one. Check what the maker says about your magazine.
• What does fail are things that are easy to check: damaged feed lips, dirty or gritty magazines, cracked bodies, rust on steel parts and followers that bind.

So the practical advice is less about avoiding compression and more about checking the magazine.

Rotation, the useful version

You do not need to unload and reload every week. A better routine:

1. Mark your defensive magazines. A paint pen or tape lets you tell them from range magazines.
2. Inspect them on a schedule. Look at the feed lips, the body, the baseplate and the follower. Replace anything damaged.
3. Fire them occasionally. Rotate defensive magazines into a range session and run them through your pistol or rifle with your defensive ammunition. Reload fresh rounds afterward.
4. Track age and use. A simple log, kept outside the lock box, helps you spot a magazine that has been through a lot.
5. Replace as the maker advises. Follow the manufacturer's guidance on service life.

Compatibility and capacity: do the homework

• Match the magazine to the gun. A magazine that fits is not always a magazine that feeds. Test each one.
• Check the law. Several states and cities limit magazine capacity. A 21-round or 30-round magazine may be restricted or prohibited where you live.
• Do not mix calibers. Keep pistol and rifle magazines clearly separate, and never load a magazine with ammunition the gun is not chambered for.

Storage: where spare magazines belong

Spare magazines are part of the household's safety picture. A loaded magazine in a nightstand drawer is a loaded magazine a child can reach. Store defensive magazines in the same locked container as the firearm, or in a separate locked container, and control the keys or code. Anything you can reach in the dark is something someone else can reach if they get past the lock. Our guide on designing storage for the household you actually have can help you think about access, and our nightstand pistol setup guide covers a typical bedside arrangement.

How many spares

There is no magic number, and nobody can tell you the right count for your home without knowing your gun, your training and your plan. A sensible baseline is one spare magazine per defensive firearm that you have tested, then add more only if your training demands them. More magazines do not fix poor habits or a missing light.

Bottom line

Choose magazines that fit your gun and your state's law, mark them, test them, and lock them with the firearm. Skip the spring folklore, trust inspection and use, and put the energy you save into identification, accuracy and storage.

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.