New to the boards, and have been reading as much as I can before I build my first AR.  I am looking to use a Stag lower, and unsure of which upper.  Going piece by piece so I can afford it (also so the girlfriend won't kill me for getting another gun).  

Questions are: Are there any uppers that will NOT fit onto a Stag lower?  What are M4 feedramps, and are they necessary?  How easy is it to assemble an upper, if I get an upper and need to add the B/BC/CH?

Thanks for the advice and answers!

Stag is a great lower, inexpensive, quality, and fit well with almost any mil-spec upper. As for M4 feedramps, they are not a neccesity. They increase reliability slightly and mainly are a benifit if you are using worn out mags or really heavy(77g and above) bullets. The military added them because of the faster cycling rate with the M4 on full auto, so on semi you should never know the difference.

Ive never built my own upper, but if you have the tools its really not all that difficult. I chose not too cause I didnt want to spend the $ on tools.

I would recomend you look at the Stag M4 uppers. Aim surplus has them, they are high quality, come with a good BUIS and are fairly inexpensive. They are 1/9 with no M4 feedramps but like I said you would never tell the difference under normal curcumstances. aim surplus

welcome to the boards

One more question... is it necessary to use a Stag parts kit or can I use any mil-spec kit?  

Yes, you can use any mil-spec parts kit.

Building an upper is pretty simple.  You will need a vice, upper receiver action block,and barrel wrench.  Look at the tacked posts at the top of this section for a step-by-step, how-to.

I built my first a few months ago and was amazed at the ease of assembly.

very good... thanks for the quick answers!