How do you find out barrel twist?

[BerksCountyDave]

Well, I recently found out that my fiance's dad is buying me a new AR upper assembly for xmas. He works in a gun shop, and I asked about availability on an upper with a 24" stainless bull barrel in flat top configuration. She told me yesterday to not buy "that gun thing you guys were talking about" because her parents are getting me one for xmas.

Now, let's say for some reason that he doesn't know what twist rate the barrel is. Would a gunsmith be able to look in there and tell me? I'd like to know so that I can select appropriate bullets when I handload for the new upper.

Thanks
Dave

[knight0334]

If you cant find it at gun/barrel manufacturer's site:

It's real easy to determine what the rate of twist of a barrel is, all you need is a tight fitting jag and patch on the end of a cleaning rod. Insert the rod in the bore from either end. Push the rod into the bore until you almost reach the other end of the rifling. Wrap a flag of tape around the rod where it enters the chamber or muzzle. Withdraw the rod slowly making sure the rod can rotate freely following the twist of the rifling. When the tape flag has rotated exactly one full turn, measure from the tape to where the rod enters the bore, that is the rate of twist.

[Lycanthrope]

Most AR's are marked on the barrel (often underneath). If not, it's usually not hard to find out based on the manufacturer.

Lycannosweatthrope