I am planning on building a kit with a RRA lower and a JT upper full kit.  My question is what barrel length should I go with (16" or 20".)  My uses for the rifle will be:
1)  Informal shooting at the range with possible local matches.
2)  Varment hunting (coyotes out to maybe 200 yards)
3)  Home defense

Given the uses would the 16" barrel give up enough accuracy and velocity that varment hunting would not be possible out to 200 yards?  I would assume that a 16" would have less velocity and accuracy but do not know how much.

Also, to all the posters on this board, GOOD JOB!  I came into the idea of an AR15 and started reading posts back for several months and I can say that it has been a huge help in figuring out where I want to go!

Jamie

For your intended purposes, I'd recommend the 16" barrel.  Yes, you will lose a little velocity, but varmint hunting should be pretty solid out to 300yds (depending upon the size of the game) and accuracy is not really affected.

Look at it this way, if you decide down the road that the 16" is not very well suited to varmint hunting, you can always pick up a 20" upper to slap on for hunting.

Have fun!

I say split the difference and get an 18" bbl.

Im planning a similar gun, RRA lower & JT upper, however am looking at a krieger (spelling) barrel. They are supposed to be very accurate. Am in the process of locating a dealer who sells them.Anyone have this info..?

Just buy directly from Kreiger and eliminate the middle delay/commission. If you want something out of the main stream, you may have to wait for them to do such a run. Two years ago I had to wait a few months for a chrome-moly steel match grade Service Rifle barrel because all in the last run of manufacture were spoken for. EXCELLENT shooting barrel.