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The ProMag SIG21 extends your P938's magazine capacity from the factory 7-round standard to 10 rounds, giving you more trigger time between reloads during training days. This makes it a practical choice if you want to maximize efficiency at the range without buying multiple factory magazines.
The SIG21 features a heat-treated steel body with a blued finish, paired with a durable injection-molded polymer follower and a heat-treated chrome-silicon wire spring. These components work together to handle repeated loading cycles. The extended design naturally makes your P938 a bit less compact for carry, but it's manageable as a backup range magazine or training spare.
New magazines often have stiff springs that need a break-in period. Many users recommend cycling the magazine through your P938 several times before heading to the range, and a magazine loader can make loading easier on your hands. Some users find the polymer extension sleeve takes time to feel natural compared to factory Sig magazines, but this is common with aftermarket options.
This magazine works well for shooters who want affordable spares for practice and training sessions. You get the practical benefit of three additional rounds per magazine at a much lower cost than factory alternatives, making it easier to stock multiple mags for extended range time.
No, the SIG21 is not compatible with Sig Sauer P938 Legion models. Legion pistols have a different magwell design that requires Legion-specific magazines. This magazine works with standard P938 pistols only.
New magazines typically need a break-in period of several loading and unloading cycles through your P938. The spring is stiff when new, so using a magazine loader and cycling rounds through the gun a few times before hitting the range helps smooth things out. Many users report it gets easier to load after 20-30 cycles.
Some shooters have reported success using Kimber Micro 9 8-round magazines in the P938, as the platforms share similar magazine dimensions. This gives you another option if you want extended capacity. However, fit can vary, so test compatibility before relying on them for regular use.
The extended 10-round capacity makes this magazine significantly larger than factory 7-round magazines, which affects how easily your P938 conceals. Most users keep these as range or backup magazines rather than primary carry magazines, as the extra length protrudes noticeably from the gun.
| UPC | 708279013324 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | SIG-21 |
| Brand Fit | Sig Sauer |
| Caliber/Gauge | 9mm |
| Capacity | 10 |
| Color | Blue |
| Length | 9.5500 |
| Model | |
| Model Fit | P938 |
| Product Type | Magazine |
| Quantity | 1 |
| Shipping Weight | 0.17 |
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