Boys, I am in a whole heap of trouble. I have a Rem XP 100 that I bought a heavy barrel for (1.27 at the muzzle) in 6.5X284. Can I "hog" out my standard Remington rear XP 100 stock for this barrel? Will the 6.5X284 fit my short action? How do I determine rate of twist for a barrel that I have no knowledge of?
HELP ME. I have fallen and I can't get up!!!

Try this to determine twist. Pull a cleaning rod with a patch or brass brush on it through the barrel and count the revolutions or portion of one reviolution over a predetermined distance and calculate from there. If the rod rotates 1/2 turn in 6 inches, the barrel is a 1:12. If it rotates 1/8 turn in 5 inches, it's a 1:40. You may not get it exactly, but you should come close enough to guess at the integer value for the actual rate. Or just wait to see what Ray Atkinson says (he's good... real good).

Alan, You have purchased a barrel blank not a finished barrel. Your gunsmith can turn it down to whatever profile you want.

No, actually that is a finished barrel. Have a look.

Well I guess it is, pretty fancy looking too.

VERY sexy!

You don't say what your XP-100 is currently chambered in, so the boltface may need to be opened up and ejection port may need enlarging, but otherwise it should fit (I know people who have .375-.284 XPs).

I would buy a used XP-100 stock to test out the material removal issues, so you don't wreck your 'good' stock.

I also use the cleaning rod method to determine barrel twist rates.

George

I have two XP's .223 reargrip and 22-250 centergrip. I was thinking of using the reargrip. Who knows, maybe I will make a 6.5 TCU and shoot BIG bullets (1:9.5 twist barrel).