What kind of rifle is it? What ammunition are you shooting? Is it clean?

As far as the clean part. If the rifle is old, there is a strong possibility that the bore has never really been thouroughly cleaned to get copper buildup out. Especially if it's what I think it is (a Spanish Mauser Model 93). I've used both Sweets 7.62 and Barnes CR-10 copper removers, and both work very well. Just follow the directions.

Also check the crown of the muzzle for damage or wear to the rifling in the first 2" or so of the bore at the muzzle. If it was cleaned routinely from the muzzle end (which was common to military rifles of that era), there is often wear around the crown or muzzle end of the bore (which is why a wise rifleman always cleans from the breech). If the crown is messed up, then accuracy will be poor.

Also try changing the ammo you're using. If you're using old milsurp ammo, which can literally be hit--and-miss accuracy wise, try some modern made factory ammo.

Good luck.

Mike