Brouwer M1811 SIG P320 Magwell Extension


Flared magwell for the Brouwer M1811 SIG Sauer® P320 Grip Module. Made from 7075-T6 aluminum, and compatible with factory 17-round (or greater) magazines.

Includes wrench and fastener for installation.


The Brouwer M1811 SIG P320 Magwell Extension is designed to enhance the already generous magwell of the M1811 Grip Module for the Sig P320. The Magwell extends the margin of error when performing magazine changes by increasing the magwell opening diameter and providing a smooth transition for feeding.

Special consideration was made to ensure that adding the magwell would maintain the same grip index and repeatability of the M1811. To achieve this, the external profile was designed to minimize impact and interference with the user’s grip.

The rear of the magwell was designed to fit below the grip profile to reduce the impact on the user’s palm swell. The front and sides of the magwell were designed to offer a secondary index point that cradles the user’s hand at the bottom of the front strap.

Brouwer M1811 SIG P320 Magwell Extension Fit Guide

  • The magwell is designed to work with factory 17-round magazines, as well as high-capacity magazines without modification.
  • Modules are designed to fit the newer style SIG Sauer magazines with the square peg. You must modify the base pads if you have the original magazines with the round peg at the base pad. Newer pads and plates are available.

Additional information

Weight .2 lbs
Dimensions 3 × 2 × .3 in


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Many parts sold by Grayguns - including but not limited to triggers, trigger kits, internal components and spring kits - are intended for installation by a qualified armorer or gunsmith who is familiar with the firearm.

Although kits fit with no issues in a great majority of pistols, Grayguns cannot guarantee perfect functionality in every instance.

Due to varying tolerances present in all mass-produced firearms, professional fitting by a qualified armorer who is familiar with the pistol's action may be required.

Grayguns offers installation services for all parts kits we offer. If you have any issues or questions about the installation process, STOP IMMEDIATELY and contact the Grayguns Customer Service Team.