The SFM (Slip Fit Magwell) is a minimalist magwell designed to increase funnel size without compromising manual of arms. The SFM was designed 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. 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 mag 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. We went through many size iterations in an effort to find what we feel is an optimal size. The SFM™ has a 170% increase in funnel size over stock.  

#2: Simplicity

We wanted to create a magwell that’s not just efficient in performance, but also in attachment and design. The 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

SFM™ is currently offered in a standard forged variant. Aero, BA, and Radian variants are being finalized.

*works with most standard forged lowers. 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.