I find the Colt conversion in my AR H-BAR shoots about 2" at 50 yards benched so its not a precision tool. I find it useful for drills like: standing, rifle at rest; raise rifle; safety off; aim and double tap; safety on; rifle down; repeat. I've never noted any leading in the barrel. I clear the rifle barrel and gas system with a few shots of 5.56 fmj.