It happend to me to i had a 700 in 30-06 i bought from a gun shop used and it would only do it here and there so you never knew when it was going to do it or not.I took it to the gunsmith and he said it was from somebody cleaning it to much. He said they put to much oil in it and it had hardend over the saftey system and the trigger system.He cleaned it and told me to spray it with something like wd-40 every so often.but it shoots fine now.