Seekins Precision SP223 Lower Receiver and Install Tips

Seekins Precision SP223 Lower Receiver and Install Tips

Info from their site.

The SP 223 Billet lower feature a unique design geared towards the serious tactical shooter. The oversized winter trigger guard, quick access mag release, beveled mag well, ambi bolt drop and user friendly features make this lower the best on the market. To ease assembly Seekins Precision eliminated the use of roll pins, hammers, punches and replaced them with custom screw in dowel pins. We installed an upper tensioning set screw, a set screw for trigger reset, relocated and retained the rear take down pin detent under the grip. Our ambidextrous bolt control allows the shooter to quickly drop the bolt or from either side of the firearm. The unique magwell design allows positive mag changes and allows the use of most all mags including Magpul P-mag and Surefire high capacity mags.

Perfectly CNC Machined from 7075 T6 Billet
Gen 2 configuration
Ambidextrous bolt release
Mil-Spec component compatible
SP Enhanced bolt catch
Upper tensioning set screw
Screw in pins in place of roll pins
Bullet pictogram selector markings
Type III Class 2 Hardcoat Anodized Finish



[flagallery gid=16 skin=slideshow align=center name=Seekins]

Click on FS to see the photos in full screen. Hit “ESC” to exit.

Seekins Precision took some initiative and modified their SP223 lower to make things easier to install the lower components. I had difficulties because I could not find any information online on how to modify the standard Lower parts kit to accommodate these changes Seekins performed.

They tapped the Bolt catch to use an screw in dowel that requires a tiny allen wrench to install and remove the bolt catch. You will need to remove the bolt catch to install the magazine catch to prevent scratching during install.


The most difficult step in setting up the Seekins SP223 lower is modifying the detent spring for the takedown pin. Springs may be sized differently between manufacturers and in this article I am cutting down an Armalite manufactured spring. Seekins Precision relocated the spring detent assembly to be vertical and retained by an allen screw instead of the traditional spring retention from the Buffer end cap.


In the picture above you can see the retention allen screw on the right side. In the pic below we have removed it.

You can also see the trigger reset set screw and the tensioning set screw to tighten the lock up between the upper and the lower assembly.


It was difficult to measure the takedown spring but this is the most accurate measurement I got for the Armalite unmodified spring.


I want to remove the amount of spring that the screw is going to replace in the chamber.


New spring length. Yours may be different. This is just what worked for three Seekins lowers I did.


Now put in your detent,

Install the spring, reinstall the allen screw and the rest of the LPK as normal and you are good to go!


If you have any questions feel free to comment below.