I am planning on building my first AR. It will primarily be used for coyote hunting in Iowa. My shots will be from 0-400 yards, but most under 150.  My questions are as follows

1. What barrel lengths should I consider. I am having Krieger build it. I had a 24", but it was a little too long for hunting in the brush. I bought a 16" upper, but it is so loud, I cant hardly stand to hunt with it. I was thinking about a 19" barrel, since Krieger doesn't charge extra for custom lengths.

2. My second question is I want to buy a 4 rail FF tube, for additional mounting surfaces. I was hoping to be able to use a carbine length tube. How long a barrel can I get by with, before I have to step into the longer length tube? I want to keep overall weight as low a possible, due to lots of walking.

THANKS SO MUCH!!!

IYM

i moved from iowa to texas in 1998 from by sioux city.  i think the 16" upper would be great with the car barrel if you are hoofing it through set aside with waste deep snow and grass.  the weight savings would be nice.  i walked with a daewoo 223 bout 2-3 miles like that and i wished my rifle was lighter.  sides like you said you are mostly doing 150 yard shots.  i also assume that you may be wearing whites to walk up on em while they sun.  course they do make a .243 upper that may be nice to use for a flat shot.

Here's something to think about:  A full length FF handguard will allow you to brace the rifle up against a broader variety of natural objects further out toward the muzzle for more stability.  A carbine length guard will limit how adaptable your grip will be for those quick shots at longer range.  Maybe a consideration at 200+ yds.

just my $0.02

Tex78

You may want to think about an 18" barrel and/or maybe a dissapator type setup where the handguard covers the gasblock.  Also you may want to check into the PRI FF tubes.  They are made from Carbon Fiber and Aluminum.  Good luck!

-Hershey