The Sig Sauer MPX is a performance-ready sub-gun with substance. Since its introduction in 2015, the MPX has enjoyed military endorsements—and a wink and a nod from car gun folks everywhere. But one novel aspect of the design that some enthusiasts loved to hate was the MPX’s translucent 30-round magazines. Those magazines were produced by Lancer for Sig. Some questioned the build quality and the price.
Fast forward to 2022 and the MPX is on its second generation. In the time between, Thril came on the market to produce their SM9 35-round magazine specifically for the Sig. Now Sig themselves have released a 35-round magazine of their own. Which should you choose? Jeremy from Gun Mag Warehouse digs into the details.
Side by Side
Side by side, the Sig factory magazine and Thril SM9 G2 magazine are identical in construction. Both have opaque, rather than translucent, polymer construction. The locking surfaces that interface with the magazine release of the MPX are located in the same place and have the same configuration. Both use steel feed lips. Indeed, the only obvious difference is the Sig logo on the factory magazine. The Thril magazine is OEM in most respects.
If you squint, however, there is one more difference. The Sig magazine has a thicker polymer base plate. The Thril magazine’s polymer base plate is reinforced with rubber. Both height and width on both base plates are identical and use the same push-button for magazine assembly and disassembly.
Which Should You Choose?
Jeremy took both the Sig and Thril magazines for a range workout and found them both to be trouble free. While we mustn’t hang our hat on a particular brand or anecdotal test to use untested gear in our own guns. In the debate between choosing factory and aftermarket magazines, the line is often blurred. In the case of the Sig Sauer MPX, the Thril magazine was an aftermarket option that was so good it became OEM. Both magazines are durable and use steel feed lips instead of polymer; the latter of which might warp can cause feeding problems. And you are not gaining any additional capacity by going from one to the other. You get 35 rounds.
If forced to choose, however, the Thril might be a better buy. If function is indeed identical, ancillary features and price become more important. In my own experience, magazines with rubberized baseplates survive abuse more readily, where naked polymer might crack open on concrete floors—especially if a partially or fully-loaded magazine is dropped. If you are working around a square range or an urban setting, the Thril magazine might continue to work if you get too clumsy. And a quick look at GunMag Warehouse inventory shows that the Thril can do that at 4/5 of the price of a functional magazine with the Sig logo slapped on it.
