just pull one bullet...dump the powder and check to see if the primer has Berdan or Boxer flashholes.

If the flashhole is more than one (berdan primed)...and the one should be in the center of the case.....in front of the primer) if there is more than one flashhole you' ll have a very bad time repriming the case, because it' s very difficult to remove the spent primer.

Assuming you have boxer primed brass, pull the bullets, dump the powder, fire the primed brass, thoroughly clean the barrel of your gun, resize and reprime and make some real ammo.

Depending on your intent, and if the bullets are FMJ, you might want to toss them as well in favor of a softpoint style of bullet.

If your brass is Berdan primed, pull the bullets, dump the powder, remove the decapping pin from the sizing die, full length resize the brass, load powder and bullets to taste. After firing the brass leave it in a trash can.