A spare magazine is not an accessory — it is a core component of a fighting handgun. A malfunction that defeats the magazine (a broken follower, crushed feed lips, a double-feed that cannot be cleared) takes the entire weapon offline unless you can strip it and insert a fresh one. Carrying a spare also doubles your ammunition capacity without adding a second weapon. Once you have reliable magazines, the next question is whether to extend them — adding rounds and improving the reload interface through base pads and magwells.
Start with OEM Magazines
The foundation of every pistol magazine setup is the factory magazine from the firearm’s manufacturer. OEM Glock magazines, OEM Sig Sauer magazines, and OEM Smith & Wesson M&P magazines are all hardened steel bodies encased in durable polymer, loaded with quality springs and followers designed and tested by the company that built the gun. Aftermarket magazines — including popular polymer options like Magpul PMAGs for Glock — are generally not recommended for carry use. OEM magazines have superior reliability track records, and reliability is the single non-negotiable quality in a magazine you trust your life to.
For Glock specifically, Gen 4 magazines are backward-compatible with Gen 3 through Gen 5 frames. Sig P365 and P320 magazines come in multiple capacity options, and the baseplate system on P365 variants lets you swap floor plates to match grip length across the P365, P365X, and P365XL — giving a single magazine platform flexibility across the entire family. One caveat: the 17-round P320 magazines are incompatible with the factory Sig Legion magwell and require dedicated Legion baseplates.
Concealed carriers should keep at least one spare magazine on the body, staged in a dedicated carrier on the belt or in a magazine caddy attached to the Sidecar holster. In a belt setup for duty or training, two pistol spares is standard. The spare magazine serves as both an ammunition reserve and a malfunction-clearing tool — the fastest way to fix many stoppages is to rip the failed magazine out and replace it.
Magazine Base Pad Extensions
Base pads bolt onto the bottom of existing OEM magazines, increasing capacity and improving the reload interface. The standard Glock floor plate has a pronounced angle that feels awkward when indexing during a speed reload. A squared-off base pad fills the palm more naturally, making it easier to guide the magazine into the grip under stress.
Arredondo +3
The Arredondo +3 adds two rounds to a Glock 19 magazine and three rounds to a Glock 17 magazine. Each kit includes a Wolff +10% replacement spring — this is not optional. The factory Glock spring lacks sufficient tension to reliably feed rounds once the tube is extended, and skipping the spring swap introduces feed failures. The Arredondo uses a clip-in retention design where the top cap clicks into retention slots on the body, a more secure system than pin-style competitors where losing the small retaining pin allows the entire base assembly to separate under recoil.
At 115mm on a G19 magazine and 130mm on a G17, the +3 extension maintains roughly the same height as the pistol itself when seated in a holster, making it practical for concealed carry. A dedicated removal tool ships with the pad and should be retained for future servicing.
Arredondo +5
The Arredondo +5 fits Glock 17-length magazines only — it will not fit compact G19/G23 tubes. In 9mm it actually adds six rounds, bringing a G17 magazine to 23 rounds. The extension pushes the magazine to 140mm, adding noticeable length below the grip that is visible in a holster. For competition and home defense, this is irrelevant; for concealed carry, it is a meaningful consideration for concealment.
Like the +3, the +5 ships with a Wolff +10% spring and a U-shaped installation tool. The only failure mode observed over years of hard use is spring wear after roughly three years and several thousand rounds — at which point the spring should be replaced. The Arredondo +5 is USPSA Limited Legal, making it a dual-use competition and defensive product.
Henning Group +6
The Henning Group extension takes a Glock 17 magazine from 17 to 23 rounds and accepts 31- or 33-round Glock magazines up to 37 rounds (using the factory spring for extended magazines). For EDC, downloading to 22 rounds is strongly recommended — loading to full 23-round capacity creates enough spring tension that the magazine can be difficult to seat on a closed slide. In competition, one magazine can be loaded to 23 to stage the gun at 22+1, with subsequent reloads at 22. The seating difficulty decreases as the spring breaks in over time. The Henning is USPSA Legal for Carry Optics, Limited Optics, Limited, and Open divisions.
Spring Rules
The common thread across all base pad extensions is the spring requirement. Short extensions (OEM Glock +2) can run the factory spring with no issues. Once three or more rounds of tube length are added, a higher-tension spring is required. Without it, the increased friction of more rounds stacked in a longer tube will outpace the spring’s ability to push the top round into the feed lips under the rapid cycling of the slide. This is a reliability failure point, and reliability is the one quality that cannot be compromised on a fighting handgun.
Magwells: Improving the Reload Interface
A magwell funnels the magazine into the grip, reducing the margin of error during a reload. Training matters more than gear here — a well-practiced shooter with no magwell will outperform a poorly trained shooter with one — but a magwell stacks on top of good technique to make reloads even more consistent under stress.
ZEV Technologies PRO Magwell
The ZEV PRO is a one-piece 6061 aluminum magwell available for Glock 17/22/34/35/37 (Standard) and Glock 19/23/32/38 (Compact). It installs with a single mounting screw and adds minimal bulk, making it practical for concealed carry as well as competition. The key advantage of the ZEV design is tested compatibility with aftermarket base pads — including the Arredondo extensions and OEM +2 floor plates. Many magwells on the market cause aftermarket base pads to hang up and fail to seat, an issue that turns a reload aid into a reload hindrance. The ZEV avoids this with internal geometry that has been verified against the common extension options.
One important limitation: 10-round magazines are incompatible with the ZEV PRO. Shooters in states with magazine capacity restrictions who rely on 10-round magazines will need to look elsewhere. Gen 4 Glock back straps may also require modification for proper fitment.
Magpul GL Enhanced Magazine Well
The Magpul GL Enhanced Magwell is a low-profile, polymer option at a fraction of the price of aluminum magwells. It is optimized for factory Glock magazines, Magpul GL magazines, and a range of aftermarket floor plates. Gen 5 Glock magazines are not compatible due to baseplate angle interference, and Gen 4 back straps require modification. If a magazine sticks on release, light sanding of the internal ledge resolves the issue. For shooters who want a minimal funnel effect without the cost or weight of a machined aluminum magwell, the Magpul is a pragmatic choice.
Compatibility Matters
The interaction between magazine, base pad, and magwell is a system, and you must verify compatibility before committing. A magwell that binds against your chosen base pad turns two upgrades into a net negative. Before buying, confirm that your specific magazine generation, base pad, and magwell have been tested together — either by the manufacturer or by your own function-checking. Load the extended magazine to full capacity, seat it on a closed slide, and run at least 200 rounds through it before trusting it for carry or duty use. Then test the reload: insert the magazine aggressively at multiple angles, confirming that the base pad clears the magwell funnel and locks in cleanly every time.
A few specific combinations to watch for:
- Arredondo +5 and ZEV PRO Magwell (G17): Compatible and widely used in competition. Verify lock-up by inserting the magazine sharply and confirming the base pad does not catch on the magwell lip.
- Henning +6 and ZEV PRO Magwell (G17): Compatible, but the additional length means more leverage on the magazine during impacts or drops. Confirm retention under stress.
- Arredondo +3 and Magpul GL Enhanced Magwell (G19): Generally compatible, but Gen 5 magazine baseplates may cause interference. Test with your exact generation of magazine body.
- OEM +2 floor plates and any magwell: Typically the safest combination, since OEM dimensions are what most magwell manufacturers design around first.
If you are running a Sig P320 or M&P platform, the aftermarket base pad ecosystem is smaller than Glock’s, and you should be even more cautious about mixing components. Stick with OEM magazines and manufacturer-recommended extensions until you can personally verify function.
Recommended Setup by Use Case
| Use Case | Magazine | Extension | Magwell | Notes |
|---|---|---|---|---|
| Concealed Carry (Compact) | OEM G19 / P365 / M&P Compact | Arredondo +3 or OEM +2 | ZEV PRO Compact or none | Prioritize concealability and reliability |
| Concealed Carry (Full-Size) | OEM G17 / P320 Full / M&P Full | Arredondo +3 | ZEV PRO Standard | Good balance of capacity and profile |
| Home Defense | OEM G17 | Arredondo +5 or Henning +6 | ZEV PRO Standard | Concealability irrelevant; maximize capacity |
| Competition (USPSA CO/Limited) | OEM G17 | Arredondo +5 or Henning +6 | ZEV PRO Standard | Verify division legality for your specific setup |
| Duty / Belt Setup | OEM for your issued platform | Per department policy | Per department policy | Many agencies restrict aftermarket modifications |
Summary
Spare magazines keep your pistol in the fight when a malfunction or an empty gun would otherwise take you out of it. OEM magazines are the reliability standard — start there and do not deviate for carry use. Base pad extensions like the Arredondo +3 and +5 or the Henning +6 add meaningful capacity and improve the reload interface, but they demand the correct spring and careful compatibility testing. Magwells like the ZEV PRO and Magpul GL Enhanced reduce reload error, but only if they work cleanly with your chosen magazine and base pad combination. Treat the magazine, extension, and magwell as an integrated system: test it together, verify it under realistic conditions, and then trust it. The goal is a fighting handgun that reloads fast, runs every time, and carries enough ammunition to solve the problem in front of you.