A bud has a bolt action Rugar M77 30/06 that is over 40 years old. He was having an issue with it sometimes with light primer hits and things not going bang until he did it a second time. He brought the bolt by for a look see as I use to own one. Firing pin looked good so I said it could be the spring but let's try something. I put in my Hornady ultrasonic cleaner in a plastic bag with the cleaning solution for 30 minutes. Well, the bag solution came out dark black/grey. So, it appeared there was a lot of old oil that was probably gummy, and this probably caused the light primer hits. We dried it out and lubed it up with WD40. He went to the range the following week and shot over 60 rounds, and everyone fired. He told me it was shooting like it was brand new. So, there is no need to disassemble a bolt to clean if you have an ultrasonic cleaner.