What don't I know about building an AR upper?

[Silverado]

My thread title is deceiving... the answer is "most everything". It seems to me though that having a number of different uppers to run on one good lower (which I have on my AR now) would be cool. Heading to the range with my rifle and bag full o' uppers!

What kind of tools do I need to do this at home? By build of course, I mean assemble from parts. No need for you cheeky machinists to tell me I need a CNC mill LOL

Tell me about your upper building experiences please.

 

[hbean]

what you don`t know is that YouTube is your friend, lots of instructional video on the subject.

 

[Timbertec]

Brownells has excellent videos about this very subject on youtube!

 

[Silveragent]

Upvote for the Brownells videos.

 

[glover]

They sell an AR Armorers Kit that has all the special tools you could need, it's like $200.

 

[jonh172]

Get books, dvds or talk to knowledgable individuals before starting.
Yes, these things are easy to build, but there are many things to know before just slapping one together, especially to troubleshoot any possible hiccups.
From proper cycling to dwell time to direction and distance of ejected brass, there are many ways to set-up an upper improperly. You can short cycle and you can overcycle your rifle.
Educate yourself and you can't go wrong!

Good luck and be safe!