S&W - Full size M&P9 2.0 | +4 Extended Baseplate

+4 Magazine Extension Base Plate 

Upgrade your reloads and grip with a durable +4 magazine extension designed to take a 17-round 9mm M&P magazine to 21 rounds while reusing the factory spring.

This extension was designed around the full-size M&P platform to provide a secure fit, added capacity, and improved handling without unnecessary bulk.

Compatible with 9mm M&P magazines only.

Why You’ll Want This

• Adds four additional rounds without changing springs

• Provides a more positive grip and seating surface

• Built for strength, reliability, and repeated use

• Clean, low-profile design that doesn’t feel oversized or awkward

Whether you’re setting up range mags, training mags, or duty-style spares, this extension adds capacity and confidence without compromise.

Product Details

The extension includes the extension body, internal spring guide, and locking tab, replacing the factory base plate entirely.

A 2.5 mm hex access hole is built into the design, allowing the locking tab to be tapped out if needed using either a 2.5 mm hex key or a small punch. This allows for clean, non-destructive disassembly if required.

No extra hardware is required.

Material

Made from PET-CF (carbon fiber reinforced PET) for excellent rigidity, dimensional stability, and heat resistance compared to standard plastics. This material was chosen specifically for functional performance, not appearance.

Fit & Compatibility

• Designed around full-size 9mm M&P magazines

• Works with compact models, though the extension will not sit flush with the grip

• Magwell compatibility is untested and not guaranteed

• Reuses the factory magazine spring

• Installs directly in place of the original base plate

Always verify smooth spring movement after installation.

Key Features

• +4 capacity increase (17 → 21)

• 9mm M&P compatibility

• Designed around full-size M&P

• Works with compact mags (non-flush fit)

• Durable PET-CF construction

• No extra hardware required

• 2.5 mm hex access for disassembly

Notes / Disclaimer

• Magazine and spring not included

• Magwell compatibility is not guaranteed

• This is an aftermarket accessory, not an OEM product

*Designed to fit OEM Smith & Wesson magazines ONLY* 

Not for sale or shipment to states with magazine capacity restrictions.