AR lower reciever width

[roguedogue]

I dont have a digital caliper to measure this so Im hoping someone will have the answer to this. What is the width of the reciever at the fire control pocket? The outside dimensions and not the fcp itself. The dimension shown by the red arrows in the attachment. My inaccurate measuring comes to .875(7/8). What is the mil spec measurement?

[xfer42]

It varies on forged. Usually around .88x. Usually ~ .9 or less on billet. These are Cerro forge that I bought a while ago. The measurements are around .001 of each other from the same die. The ones that are clearly from a different die (Cerro Forge keyhole in different position) can be as much as .01 different.

[kcstott]

there is no call out on the width of the part. at least not from my 1970's ordinance drawing

[ar15barrels]

7/8" is the nominal dimension.

[Nathan Krynn]

there is no call out on the width of the part. at least not from my 1970's ordinance drawing

KC is right. There is no width, nor wall thickness doe to no width spec.

There is a normal range but this is one of those spots that people swear there is a spec for that there is not.

[ModulusArms]

You are right, there is no spec for the width. This is why Universal Jigs for 80% lower receivers did not exist until we came up with one. Please see the video below.

[kcstott]

You are right, there is no spec for the width. This is why Universal Jigs for 80% lower receivers did not exist until we came up with one. Please see the video below.

The original universal jig was a Bridgeport, a Kurt vise, and a edge finder.

[ModulusArms]

Haha! I will say that's not a Jig. That is above and beyond. It's dedication!

[kcstott]

Keep in mind that statement comes from a guy that did his own lowers from 10% paperweights before I even knew there was a such thing as an 80% lower

[ModulusArms]

Keep in mind that statement comes from a guy that did his own lowers from 10% paperweights before I even knew there was a such thing as an 80% lower

Then our Jig would be like child's play for you! Obviously more dedicated and talented than most. Nice work!