Your AR building checklist, made easy:
Lower Receiver Assembly:
Lower Receiver
Lower Parts Kit (LPK)
You have three options when choosing a LPK:
Grip (if not included in your lower parts kit)
Parts you need for a functioning buffer kit:
- Buffer Tube (Midlength and Carbine length gas systems utilize a carbine buffer tube, rifle length gas systems require a rifle length buffer tube.
- End Plate
- Castle Nut
- Buffer Spring
- Buffer
Fire Control Group (if not included in your lower parts kit)
Upper Receiver Assembly:
Upper Parts Kit (UPK)
Parts needed for a complete upper receiver:
- Complete UPK
- Ejection Port Cover
- Forward Assist (Confirm your upper needs a forward assist, for example).
Please note your barrel choice’s “gas block journal” diameter.
Please note the barrel’s gas system length (pistol, carbine, midlength, rifle), this will need to match the gas tube length.
Make sure your gas block diameter matches your barrel’s “gas block journal” diameter, both are typically measured in inches.
This will need to match the gas system length of the barrel.
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