Mikewalker is right. If you haven't fired it though, don't. If you have fired it, carefully inspect your cases for odd dents, indicating some junk stuck in the chamber. My new '94 came from the factory with a hard chunk of gunk stuch firmly in the chamber, which showed up as a dent near the shoulder of each fired case. After I cleaned it out (which took a great deal of effort) headspace was way long and I had to send it in for headspacing. Seems it was originally headspaced with the gunk in place.
Yours is older, so it may be something completely different. If a super good cleaning of the chamber, bolt and lock-up mechanism doesn't help, its definitely a job for an experienced gunsmith. For one thing, they can tell you in about 2 seconds, using a "go, no-go" gauge, whether the headspace is in spec.