22'' barrel vs 24'' barrel

[Road_Clam]

So, barrel length has little to do with accuracy. If I want to build an accurate AR15 in 223/556 what do I have to get?

I am a complete newb to the AR platform although I have been shooting bolt rifles for over 50 years. The gun will be used for three gun competition.

If your intent is 3 gun I would suggest a 18 or 20". 3 Gun can vary greatly in distances so the 18" barrel will get you all the way out to 500 yds, the 20" will get you to 600 yds. I would do some local to you research on 3 gun and find out what distances they shoot at. If your only going to shoot <100 yds then a 16" carbine will serve you well. You're also going to have to plan for an optic. Either a 1-6X scope or a dot should work nicely. I would also suggest an 1-8 twist barrel so you can shoot up to 69 gr match bullets. If you find you will be shooting 500 or 600 yds then I suggest a 1-7 twist so you can shoot 77 or 80 gr bullets. Good luck on the build !