My brother bought a model 60 at an auction years ago. Brought it home and tried to shoot it. The bolt wouldn’t go forward when tried to cycle by hand, had to push the bolt handle to get it into battery. He then tried to shoot it and the bolt stuck open. He brought it to me to see if I could fix it. When I took it apart the inside of the receiver, bolt and trigger group was thoroughly gummed and caked up with unburnt powder and general nastiness. Let it soak overnite in Hoppes and cleaned it and it functioned perfectly. Obviously it had NEVER been cleaned.
Unfortunately kids and young people do this, I did with my first 22. But fortunately it always fired,it's a 552 speedmaster and I still have it.