Description
The ProMag P320 drum magazine gives you serious firepower when you're spending long days at the range or want to minimize reload frequency during training. Loading 50 rounds of 9mm into a single magazine changes how you approach your practice sessions, especially if you're pushing through drills or testing accuracy at distance without constantly swapping mags.
Construction and Durability
This drum magazine is built with a proprietary DuPont Zytel polymer drum body paired with a blued steel upper magazine tower. The magazine upper tower features a full-length steel internal insert that's stamped and welded just like factory SIG magazines. Inside, you get an injection-molded polymer follower and a heat-treated stainless steel magazine spring to manage the round count reliably.
What Sets This Drum Apart
The engineering behind the P320 drum magazine addresses what drum mags need to do well: feed consistently, handle high round counts without binding, and hold up over time. The steel components where it counts and the polymer body keep weight reasonable compared to all-steel alternatives. ProMag backs every magazine with a lifetime warranty against manufacturer defects and manufactures this mag in the USA.
Range Ready
With 50 rounds on tap, you can run longer strings of fire, practice more complex shooting sequences, and spend less time reloading. The drum format sits lower in the magwell than some extended stick magazines, which some shooters prefer for how it feels in their hands during use.
Key Specifications
- Manufacturer: ProMag
- Manufacturer Part Number: DRM-A55
- UPC: 708279015274
- Caliber: 9mm
- Capacity: 50 rounds
- Magazine Type: Drum
- Compatibility: SIG Sauer P320 9mm
- Color: Black
- Magazine Body Material: DuPont Zytel polymer
- Magazine Tower Material: Blued steel with internal steel insert
- Magazine Spring: Heat-treated stainless steel
- Follower: Injection-molded polymer
- Warranty: Lifetime against manufacturer defects
- Made in: USA
- Shipping Weight: 1.74 lbs
What’s Included
- ProMag 50-round drum magazine
Frequently Asked Questions
Will this drum magazine fit my full-size P320?
Yes, the DRM-A55 is designed to work with all SIG Sauer P320 full-size, compact, and carry frame models in 9mm. The mag will extend below the grip when used in a compact frame, but will function properly. Always verify your P320 is chambered in 9mm, as this magazine is caliber-specific.
How reliable is the ProMag P320 drum magazine?
ProMag has refined their drum magazine design over years, and the P320 version incorporates features like a steel magazine tower with internal insert, precision-wound heat-treated springs, and an injection-molded follower. The company backs it with a lifetime warranty against manufacturer defects. Like any high-capacity magazine, it benefits from function testing before carrying or relying on it in critical situations.
What's the advantage of a 50-round drum over regular extended magazines?
A 50-round drum lets you fire significantly longer before reloading, which is great for extended training sessions or range time where minimizing magazine changes matters. The trade-off is that drums are wider and slightly bulkier than stick magazines, so they change how the pistol feels in your hands. For competition or defensive use, most shooters stick with 21 or 30-round extended mags instead.
Is this magazine legal in my area?
Magazine capacity laws vary significantly by location. Some states and municipalities restrict magazine capacity, while others have no restrictions. Before purchasing, check your local regulations to ensure this magazine complies with the rules where you live and shoot.




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