24" Barrel lightweight AR build?

[Squirrelmarm]

... to be precise i'd have to look it up, but if i recall it was in the 50 to 75 fps range depending upon bullet. i.e. speed did favor the 24" tube for me, but the gain over the 20" wasn't astonishing.

Thanks for your comment, if the velocity gains are so minimal I might go with a 20" barrel after all. Weight savings is more important to me. My current build is 9lbs with an 18" barrel, I think it's too heavy. Like I said I'm more just scoping things out at this point, I will probably start on this build sometime next year.