Magpul UBR 2-Stage Lower Build Kit

The Magpul UBR 2-Stage Lower Build Kit includes everything you need to finish your lower receiver, including the brand-new Dirty Bird 2-Stage Trigger Group.

Magpul UBR GEN 2 Adjustable Stock

• Mounts on a durable custom Receiver Extension tube (included) to accommodate carbine buffers and springs as well as aftermarket A5 buffer systems*
• Solid “fixed stock” lockup and consistent cheek weld in all positions
• 7 adjustments plus fully collapsed for 8 total positions
• Adjustment lever requires only gross motor movement to operate yet the entire stock remains streamlined and anti-snag
• Enhanced lock mechanism with dual locking pawls for maximum drop strength and shock resistance
• Multi-shell construction provides solid foundation and shields critical operating parts from penetration damage
• Sloping cheek weld combines a slim profile with user comfort
• Storage Compartment in tail of stock is removable and the door is reversible for user preference
• Rubber butt-pad offers an anti-slip surface and increases impact protection
• Rollover on the toe allows for easier shoulder transitions and better fit when using body armor
• Sling Mounts
  • Front – QD swivel mount for ambidextrous one-point QD sling mounting
  • Left/Right Rear – Rotation-limited QD swivel sling mounts fit up to 1.5″ push-button swivels
  • Bottom – 1.25″ sling loop (additional loop accessible when Storage Compartment is removed)

Dirty Bird 2-Stage Trigger Group

This trigger assembly takes advantage of a two stage fire control design that has been trusted in both competition and combat roles for decades. Springs are tuned to provide a smooth first stage pull of about 1.5lbs and a crisp second stage break at 3lb for a total pull weight of 4.5lbs (actual total pull weight may vary ± .5lb). The 4.5lb total weight gives the operator a greater level of safety and control in high stress environments but with a second stage pull weight of only 3lbs, the shooter can also squeeze of long range precision shots with ease.

Magpul MOE-K2+ Grip

• Replacement for AR15/M4 pistol-grip*
• One-piece reinforced polymer construction with wrap-around rubber overmolding
• More vertical grip angle than standard A2 grips
• Unique backstrap design for proper trigger finger placement
• Hard-polymer bottom edge to reduce equipment snags or grip damage
• Includes a basic grip cap, but accepts optional Storage Cores for customized gear stowage

Dirty Bird AR-15 Lower Parts Kit Minus FCG & Pistol Grip

• 100% American Made Kit
• Includes extra takedown / pivot pin detent and detent spring
• Includes enhanced polymer trigger guard

Mil-Spec AR-15 Carbine Buffer Spring

KAK AR15 Standard Carbine Buffer