KE Arms KP-9 Polymer Complete Lower Receiver with SLT-1, SLT-2, or RTS-1 Trigger

Please read this entire document prior to use.

WARNING! DO NOT Dry Fire your KP-9 without the upper in place. Doing this can damage the receiver wall in front of the hammer.

Note: After first range session, remove buffer assembly from lower receiver by pressing down on buffer detent and pulling out buffer and spring. The cycling of the action may have removed additional plastic flash caused by the manufacturing process that was not removed during our post-weld processing. Shake out any debris or use compressed air to clear out the buffer tube.


• The KP-9 has a lifetime warranty for normal use.

• Sling Attachment points wearing out is not grounds for a receiver replacement.

• If the receiver breaks through misuse or neglect, we will replace it ONCE for $65.00.

• Structural modifications including stock shortening and removal of material and dyeing the receiver void the warranty.

• If you intend to register your KP-9 as an NFA weapon test it thoroughly before doing so in a Title 1 Configuration. Once you Form 1 or Form 2 it, you are legally the manufacturer and we cannot service or support it as easily. Should your receiver require warranty replacement we can only replace it with a title I receiver and we are not responsible for tax stamps or NFA fees.

• Cerakoting: If you intend to have your KP-9 Cerakoted we recommend you use Pro 2 Customs as they are experienced in coating polymer receivers and have our authorization. The bake should be done at low temperatures (<190 Degrees F) and with an upper in place to prevent warping.

Technical Notes

• The KP-9 receiver uses a Carbine LENGTH buffer and spring. A standard 5.4oz 9mm carbine buffer is included in your unit. Do NOT use anything other than 9mm carbine buffers and round springs or the 9mm JP SCSS in the KP-9. Use heavier buffers as long as your gun can cycle reliably. Failure to use this minimum buffer weight of 5.4oz can damage the lower.

• The front lugs where the upper receiver attaches are intentionally snug. The upper should be pushed down in place from the top between the lugs. The rear take down pin may need to be tapped in and out with a hammer depending on upper fit.

• The Take Down and Pivot Pins have the detents built into them; eliminating the spring and detent holes in the lower increases durability. Pins insert left to right. Spare pins are available from KE Arms.

• The buffer detent is held in place with a 5/64” x 1” Roll Pin

• Your receiver comes with an SLT-1, SLT-2, or RTS-1 Sear Link Technology Trigger Installed. These triggers offer a number of benefits including the ability to put the firearm on safe regardless of hammer position.

• The hammer pin area is wider for durability. Your receiver includes a special long hammer pin. Standard AR15 hammer pins can still be used but we offer a longer hammer pin for customers preferring a flush pin for aesthetic reasons.

• Your receiver includes a KP-15 Optimized Ambi 90/45 degree selector set to 45 degree mode. Disassembly of the fire control group should only be done by an experienced gunsmith or certified armorer. Safety selector spring and detent load from the top and then the selector is slid over them. Removing the selector arms reveals the easy disassemble notch half way between safe and fire. The selector can be pushed out in this position after the fire control pins have been removed.

• The bolt catch will NOT work for last shot lock back unless you use an upper with a linkage system to interface with the Glock magazine follower.

• The bolt carrier group you use must be one that is machined to clear through Glock magazine feed lips.


Magazines NOT locking in OR Upper CANNOT Close

1) Loosen the screws that retain the ejector on the left side of the receiver

2) Insert an empty magazine

3) Close the upper onto the lower

4) The Ejector should now be centered between the top of your magazine and the bottom of the bolt carrier group, allowing magazines to lock in, and the upper to close and the bolt carrier to move freely

5) Tighten the screws that retain the ejector

Upper still CANNOT Close or Bolt Carrier will not move

Though we strive for as much cross compatibility as possible, unfortunately there is no industry wide spec for Glock magazine fed 9mm AR15s. Some bolt carrier groups have a track that is too narrow for our ejector or the track is offset vs the ejector location. In these cases the ejector can be fitted to the particular bolt group and will run properly with sufficient clearance. Contact KE Arms at for further guidance/instruction.

Further technical assistance can be had by e-mailing