Originally Posted by mach1337
Question. I have been reading alot of build threads and in alot of the you all recommend building your lower and buying a complete upper. Why is that? Im 99.99% sure that if i can disassemble my 351w in my bronco or do a complete build of my 77cj5 that i can put together a upper reciever.
Havin said that Im looking at gettin my lower to start piecing together my ar. tryin to keep the total build around 1k-1200 whats a good lower to get?
The reason you see recommendations on buying an upper is merely because of the gas system and the timing. It's not difficult, but it can be frustrating if you get the wrong part. Also, with a purchased upper, you get the benefit of having it correctly headspaced, timed and tuned. On a build, you have to do that.
How hard is that? It isn't. The AR barrel has a shoulder on it, and the lower receiver has a lip. You insert the barrel to the lip and it's 98% of the time headspaced correctly. Very rarely do you have a problem.
On the timing, well, you can encounter issues as there are several different size and weight springs that go into the math, but usually you can swag it out pretty close.
So, to answer your question, it's safer for the forum to recommend a tuned upper because of liability issues.
Any lower that isn't pot metal chinese crap will suit your needs. Anything that is forged is fine, anything that is CNC Billet is better, but much more expensive.