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Need some help with a build

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So I picked up this lower in December.  Not getting very good feedback from the vendor because I'm having an issue with it not mating up with the jig I bought.  The one on the left is what mine looks like.  The one on the right is what it should be to fit with the jig.  Can someone please tell me what the hell I bought?

As you can see the extra meat under the front hole is what is causing my issues.  


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Righttobear was the vendor for the lower.  JTactical (Juggernaught) was the maker of the Jig.  Jtactical offered to alter the jig for free, but what I really need to know is WHY the difference between the two.

Righttobear sent me to a website with Jigs, but all of the ones they show have the lower on the right.  Why are they different?


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I've built on one similar to the one on the left at least once, it did fit in the 5D pro jig so I didn't notice the difference at the front until you mentioned it here and I went back and looked at a photo. Nothing wrong with it, "Billet" (milled from a forged billet) instead of just "Forged" like the one on the right.  Fit the DPMS pattern upper fine. 

image.png.b28880fefe7ccb214e75c73f76b4e5bd.png        image.png.2888a25d3144dd32050b7342a7ea2d6e.png

Edited by Albroswift
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As to the WHY and “have the lower right” comments, those are some of the things you see when dealing with the large frame. There is no mil spec for large frame AR’s and companies wind up doing whatever they want. In many cases, they’re probably trying to NOT be an identical copy of someone else’s for legal reasons (but that’s just speculation on my part).  The differences between all of the different manufacturers is why you’ll see it recommended to keep uppers and lowers from same manufacturer when possible to limit headaches. We have to be really careful that we watch the nomenclature when looking for parts or even reporting on our own stuff. The Armalite, DPMS, RRA was tough enough…throw in 30 other minor variations from other companies and watch heads spin. 

Your lower is not wrong. It’s the style they went with. As for why they didn’t  have the jig specifically for that one on R2B…don’t know. 

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