2 years ago I bought a RRA lower in the hopes of building my first ar15.  Well, other things came up and that never happened.  Anyway, I decided that it had been sitting on my shelf for long enough, and I’m finally going to build my gun.  I’ve pretty much picked out all the parts I need, I think, but I’m stuck on what barrel and twist rate to get.  1:9 or 1:7

Also, will these parts work together ok, and am I missing anything really important?  By the way, I have no clue on what I’m doing.

Thanks!


RRA Forged A4 Upper Receiver Assembly
Barrel??
LMT Bolt Carrier Group
7.0" LaRue Tactical Handguard  
MagPul Gen 2 trigger guard      
Phantom - 5C2  flash hider
Magpul Ranger floor plates
Magpul CTR Stock
Milspec Receiver Extension (Buffer Tube)                
H Carbine Buffer
Carbine Action Spring
Magpul MIAD Grip – BASIC
TangoDown Vertical Grip - Black
Magpul CTR Rubber Buttpad BLACK

A gas tube and block will help keep it from being a One-Shooter As for barrel twist, you will probably not tell the difference unless you go real light on the bullet. Think 1:7 50 to 75 grain and 1:9 as 40 to 70 grain. So, more than likely, you will be shooting stuff in the range that either work well. Have fun.