Dirty Bird DB9 9mm MP5-Style Billet Lower Receiver

The DB9 MP5 Billet Lower Receiver is an ideal choice for starting your 9mm AR build. Precision machined from a solid block of 7075-T6 billet aluminum and finished with hard-coat black anodizing per Mil 8625 Type 3 Class 2 specifications, you can be sure that this unit is as tough as they come.

This lower receiver accepts most metal MP5 style small frame pistol caliber magazines in 9mm and the mag well features a beveled feed lip for quick and easy mag swaps. Extensive testing and attention to detail also ensure that your MP5 magazines will drop free when released. The proprietary magazine catch and ejector is included and from the factory.

Other features include:

• Machined from 7075-T6 aircraft grade billet aluminum
• Matte black hard-coat anodized per Mil 8625 Type 3 Class 2
• Precision machined magazine well with beveled feed lip for easy mag swaps
• Machined and engraved to be compatible with 45 and 60-degree short throw fire control selectors such as the BAD_ASS ST 45 Lever
• Compatible with most standard AR-9 components and most aftermarket parts
• Take down pin spring and detent hole is threaded for a 6-32 set screw for easy capturing (hardware included)
• Upper tension screw behind grip screw (threaded hole with hardware included) to adjust any “slop” out of vertical fit between upper and lower
• Ambidextrous trigger finger rests with grooves (above and below mag release/mag catch)
• Threaded bolt catch pin (Threaded hole and hardware)
• Integrated large opening “winter” trigger guard
• Limited Lifetime Warranty

Important information:

Magazine Compatibility

The lower was designed to fit and drop free factory MP5 9mm magazines. It has also been thoroughly tested with many aftermarket magazines to fit and drop free. Although it accepts and shoots other aftermarket magazines (KCI, etc) some slight modification may be needed to get them to drop free from this lower because of the varying width measurement we have seen when checking these magazines to H&K MP5 factory specifications.

Bolt Carrier Group (BCG) Requirements

You’ll need a BCG which is compatible with Glock style magazines. Some BCGs in the market are compatible with both Colt and Glock style magazines but some others are specific. The difference is Glock magazine compatible BCGs have the relief cuts necessary to clear the magazines.

Lower Parts Kit Compatibility 

Any mil-spec or better LPK will work but you won’t need the mag catch assembly, bolt catch roll pin or the trigger guard as those are all included with this lower.

*Proprietary parts are included but not installed from the factory.