Only the shooter knows for sure. If you have a load that has proven accurate in this barrel previously you can shoot it, or if you've never fired this barrel you can try some different loads through it to see what it will do. Generally, if you shoot the barrel and it doesn't give the accuracy you believe it capable of a quick look (before the rifle is cleaned) at the muzzle end will show if the crown is faulty. It will show powder residue in an uneven pattern around the muzzle, or on one side only. Just remember this isn't some exact science but it is an indicator of a messed up crown.
