Merry Christmas. Its sounds like a bad bullet did disintegrate in the barrel leaving enough lead to cause the problem you had. Scarey situation. lucky that it wasn't worse. I would test fire it one round at a time & do a visual inspection after each shot to make sure the problem isn't caused by the rifle. Check each round before it is chambered to see if its ammo related & /or call S&W for expert advice. I shot 300 plus rounds through mine with about 1 jam up per 25 rounds for the first 100 or so rounds but no issues after that since. I did remember I had one jam & when I ejected the cartridge the bullet was bent on an angle. This was with Winchester 22lr varmint ammo. Rifle seems flawless now. Perhaps a break in issue??
Be cautious.