In addition to what Riderdie and BikerTrash said:
I don't know anything about the PSA lowers, but I would probably trust them just cause of their reputation. I ordered a Spike's lower (spikestactical.com) from AIM Surplus: aimsurplus.com
I haven't ordered my upper yet, but am 99.99% sure i'm going with a BCM upper: bravocompanyusa.com
It was between BCM and spike's for the upper, but BCM's quality is 2nd to none. and it helps that my upper is on sale for around $520 (originally $800).
Whatever you do on your build, a) buy quality stuff and b) build what you like and c) be practical, not tacticool.
edit: if you're looking to drop a few g's, LWRC is the ****, but $$$$. you can also drop some serious coin on LMT and Noveske.
I don't know anything about the PSA lowers, but I would probably trust them just cause of their reputation. I ordered a Spike's lower (spikestactical.com) from AIM Surplus: aimsurplus.com
I haven't ordered my upper yet, but am 99.99% sure i'm going with a BCM upper: bravocompanyusa.com
It was between BCM and spike's for the upper, but BCM's quality is 2nd to none. and it helps that my upper is on sale for around $520 (originally $800).
Whatever you do on your build, a) buy quality stuff and b) build what you like and c) be practical, not tacticool.
edit: if you're looking to drop a few g's, LWRC is the ****, but $$$$. you can also drop some serious coin on LMT and Noveske.