I don't completely know the difference between the two. Is it in the sights ? Is the A2 more popular for any reason ? Why do people still want the A1 ? I need someone to tell me the pros and cons of each of these uppers as I don't know the difference. Also, while I am thinking about it, what is the difference between the A3 and the A4... they both are flat tops, so whats the difference ?
Sorry about the noob questions......

A1 has sights which are not very adjustable and therefore more rugged and cant get knocked out of whack.  They are actually superior for a combat rifle.  The A2 is better as a target rifle.  The A1 can be less expensive and it is lighter.

You want to swap in an A2 front sight post and A2 rear aperature into the A1 upper though.

Some manufacurers call a flat top an A3 some an A4 no difference.  Then there is the M16A3 and A4 but thats unrelated.  The uppers are the same thing.

thanks for the info. I think I understand now, I thought it was just a difference in sights.

I changed both my A2's for A1/C7's, because of the A2 sights, the A1/C7 is [b]my[/b] preference.

Also; [url=groups.msn.com/TheMarylandAR15ShootersSite/whatisana1a2a3ora4.msnw]Whats an A1, A2, A3, or A4?[/url]