Re-brand from We Plead The 2nd, we are now Pro 2 Customs !

phone: 480-968-2182

KP-9 Complete Lower Receiver

MSRP: $249.95
( saved $24.95 )
No reviews yet Write a Review


The KP-9 is a monolithic polymer 9mm Glock Mag Compatible AR15 style receiver made from injection molded 30% glass filled nylon incorporating the buttstock, buffer tube, pistol grip, and trigger guard into the receiver design as integral components.  

This manufacturing process offers several advantages

  • Lighter weight compared to similarly configured receivers
  • Lower cost to similarly configured receivers

Features Include:

  • Compatibility with most common 9mm AR15 uppers and lower parts kits
  • Compatible with Glock 17 and 19 Magazines
  • Flared magwell to make reloads under stress easier to perform.
  • A1 Length 13” Length of Pull (LOP) Buttstock to fit a wide range of shooters
  • MLOK Slots at rear of stock for sling attachement points or run a strap through it for simple sling attachment
  • Holes at the front of the stock for QD socket inserts for more sling attachment options
  • Improved grip for comfortable use
  • “Winter” Trigger Guard

Completed Lowers Include:

  • Mil-Spec Fire Control FCG and Optimized Selector, or upgrades available
  • 5.4oz 9mm Heavy Buffer and Spring
  • Bolt Catch Assembly*
  • Pivot and Take Down Pins
  • KP-9 Selector Detent
  • Buttplate
  • 5/64" Roll Pin to Retain Buffer Detent
  • Ambi Glock Magazine Catch Assembly
  • Adjustable 9mm Steel Ejector

Technical Information

  • The KP-9 receiver uses a Carbine buffer and spring. Do NOT use anything other than standard 9mm carbine buffers and round springs or the JP SCSS in the KP-9.
  • The Take Down and Pivot Pins have the detents built into them; eliminating the spring and detent holes in the lower increases durability.
  • The buffer detent (should you choose to use it) is held in place with a 5/64” Roll Pin
  • The KP-9 is compatible with all Mil-Spec Fire Control Groups
  • The KP-9 is compatible with cassette style match triggers including the KE Arms SLT units. The retention system of these triggers with D-Clips in the bushings to retain the fire control pins makes them better suited for use in the KP-9 than other designs that require captured pins.*
  • The hammer pin area is wider for durability; Standard AR15 hammer pins can still be used but we offer a longer hammer pin for customers preferring a flush pin for aesthetic reasons.
  • Safety selector spring and detent load from the top and then the selector is slid over them.  Standard selectors can work but removing them can be particularly difficult.   We recommend the use of our optimized mil-spec selector or optimized ambi selector to make removal easier.  Follow our assembly guide for further instructions.
  • The KP-9 is compatible with 9mm blowback systems with a 5.4oz carbine buffer minimum.  Use heavier buffers as long as your gun can cycle reliably.  Failure to use this minimum buffer weight can damage the lower.
  • CMMG Radial Delayed Blowback Uppers will need modifications to the ejector to work.

Last Round Bolt Hold Open
Last Bolt Hold Open Functon is dependent upon the upper you use. The standard bolt catch does not interface with the Glock Magazine follower. Some uppers such as those from Gibbz Arms and New Frontier Armory have linkage systems that interface with the Glock magazine followers and extend back to the bolt catch. Without one of these uppers, the bolt catch can still be manually actuated to verify a clear firearm or make inserting a magazine with high tension easier.

* Match Trigger Compatibility.  
The front lower portion of the KP-15 fire control area has a radius.  This is a fact of plastic design for mold release and strength.  Some cassette style triggers with large housings that fill the entire fire control group may not fit.  Do not force a cassette trigger into place; you may damage your receiver doing so.

Known Compatible Match Triggers
KE Arms SLT-1
KE Arms SLT-2

Known Incompatible Triggers
Triggertech- Does not fit in fire control pocket; holes do not line up due to housing size.
CMC- Does not fit in fire control pocket; holes do not line up due to housing size.


Individuals please use the following steps when purchasing a firearm or lower receiver:
- Have info of FFL you want your purchase shipped to ready prior to placing order
- Business name of FFL (Name on license) and FFL’s address needs to be entered into the shipping info upon checkout.
- Have receiving FFL email a copy of their license to (orders will not be processed until a copy of FFL is received)
- Please be aware of any state or local laws that may pertain to your order.

Lifetime Warranty through KE Arms