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  • $54.99

The SFM is available at:

Driven Arms Co

OP Tactical

Weapon Outfitters

OTN Solutions Group

The SFM™ is a patent pending magwell designed with a minimalist approach to increase funnel size without compromising speed of other actions. We designed the SFM with a few key points in mind.

#1: Efficiency

The SFM allows for improved reloads while using Night Vision or when close focus is impaired. Night Vision has a fixed focal plane, meaning if objects in the distance are in focus those that are up close will not be. Having a larger funnel size is hugely beneficial here as it compensates for margin of error in insertion due to lost close focus. Thinking a step further; having a large funnel is great, but the larger it is the more potential it has to be counter productive to a smooth reload. It’s not just about insertion. If the funnel is too large it can impede your ability to hit the bolt catch. Not everyone reloads the same way, but many slide their hand up after inserting a mag. Having a funnel too large impedes your ability to slide your hand up smoothly, slowing down hitting the bolt catch. Or potentially blocking your thumb from pressing inward as freely. We went through many size and shape iterations in an effort to find what we feel is an optimal size. The SFM™ has a 170% increase in funnel size over stock. There is also a slight taper towards the rear of the SFM allowing just a bit more freedom to slide your hand up for bolt catch engagement or pressing your thumb in.   

#2: Simplicity

We wanted to create a product that’s not just efficient in performance, but also in attachment and design. The Patent Pending Slip Fit™ attachment method is simple, lightweight, and secure. Using a single 4-40 socket head screw, weight is kept to an absolute minimum. The screw doesn’t require loctite as the way it attaches imparts positive tension onto itself, acting as a lock washer. However, if you are someone who loctites everything a single drop of blue will be more than enough. The SFM™ naturally grips the stock lip and will not come off unless forcibly peeled away. Overall it’s a simple yet very secure design.


  • Includes 3/32” Hex Key
  • Durable single piece nylon construction
  • Simplified hardware reduces potential failure points to effectively none
  • Ultralight construction: 0.49 oz including hardware


  • Max Length: 3.37 in / 85.59 mm
  • Max Width: 1.74 in / 44.19 mm
  • Max Height: 0.64 in / 16.25 mm

The SFM was developed with the help of Driven Arms Co. They offer several variations of the SFM.

*works with most standard forged sets. If yours isn’t a standard forged it likely won’t work. For E1/BA Enhanced, please purchase the specific variant. If you have any trouble when installing your SFM please contact us for assistance. Due to the efficient attachment method, minimal torque is needed when tightening the screw. Simply tighten the screw until the split section begins to touch, then just shy of a 1/2 turn of the screw for final torquing.