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The ProMag RM40SL steps up your AR-15 game without overcomplicating things. You get 40 rounds instead of 30, which means fewer reloads at the range, in competition, or during training sessions. That translates to more time shooting and less time breaking your rhythm to reload.
Under the hood, this magazine uses a combination of proven components. The body is made from DuPont Zytel polymer, a material that's both durable and lightweight so loading 40 rounds doesn't become an arm workout. What really matters for reliability is what happens inside: stamped steel feed lips and catch are over-molded directly onto the polymer body, creating reinforced contact surfaces where they count. The magazine also features a patented anti-tilt roller follower and a chrome silicon wire spring that's heat-treated for consistent tension.
The roller follower is the key to consistent feeding throughout the entire mag. It reduces friction and prevents rounds from nosediving under pressure, whether you're loading the first round or the fortieth. The chrome silicon spring is engineered to handle thousands of compression cycles without losing tension. Real users report flawless performance across different ammunition types and multiple AR platforms.
ProMag designed this magazine specifically for range shooting, training, and competitive applications. The magazine is backed by a lifetime warranty against manufacturer defects. Made in the USA, the RM40SL fits standard AR-15 platforms and is compatible with .223 Remington and 5.56 NATO ammunition.
Yes. The RM40SL uses the same reinforced feed lips, anti-tilt roller follower, and heat-treated spring that you'll find in quality magazines from larger manufacturers. The key difference is price. Users report flawless feeding across different ammunition types and AR platforms without any special modifications needed.
DuPont Zytel polymer is a high-performance material that offers some real advantages. It's lighter than metal, which matters when you're carrying full magazines. It also resists denting better than aluminum, which can become damaged and stop feeding properly. The steel-lined feed lips and catch on this magazine give you the durability of metal where it counts most.
The patented anti-tilt roller follower reduces friction as rounds feed into the chamber. This means smoother, more consistent feeding from round one to round 40, regardless of how many rounds are left in the magazine. It's a design that prevents double-feeds and nose-dives that can happen with standard followers under high spring tension.
The chrome silicon spring is designed for thousands of compression cycles, and the polymer body resists wear from regular use. With proper care and maintenance, you can expect years of reliable service. ProMag backs the magazine with a lifetime warranty against manufacturer defects.
| UPC | 708279014512 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | RM-40-SL |
| Caliber/Gauge | .223 REM/5.56 NATO |
| Capacity | 40 |
| Color | Black |
| Model | |
| Model Fit | AR-15 |
| Product Type | Magazine |
| Shipping Weight | 0.735 |
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