Who hasn't encountered a bottle of beer that had become over carbonated? What do you do when you realize your batch of bottled beers are over-carbed (e.g., bottled too soon before reaching FG)?
A practical pearl regarding dealing with over-carbed bottles exploding and how to safely diffuse the situation. If you don't know the amount of overcarbonation--assume the worst, e.g., champagne-like levels in a bottle not designed for the purpose.
Safety first: Protective eye wear (and face shield), clothing, shoes, and gloves would be advised while handling the bottles. Wrapping the bottle with a thick towel adds another layer of protection during handling and processing. Careful handling and placement of the bottle onto surfaces is also wise.
1.) Chill the bottles down to refrigerator temps. Reasons to do this are: a.) to drive the excess CO2 into solution and b.) slow down/or stop fermentation (and further CO2 production).
2.) Once chilled, take one bottle at a time to a utility sink, set it down inside the sink, spray starsan around crown and neck of bottle, and carefully pry off the crown w/o bending the crown too much. At a minimum, eye glasses and gloves are suggested for safety. A thick towel loosely wrapped around the glass would also help absorb a bottle explosion if it should occur during handling or decapping.
3.) Excess gas will escape, some beer will foam and escape the bottle, as well. Expect to lose an ounce (or even more) if the beer is chilled; however, a warm over-carbonated beer may rapidly disgorge the entire contents of the bottle when opened. A chilled beer will retain some carbonation after recapping and keep the remaining beer reasonably carbonated. If excessively over-carbonated, you may still lose the entire contents of the bottle regardless of beer temp.
4.) Push down on the crown and recap with bottle capper. If the crown falls off, squirt star san onto both sides of the crown and recap.
5.) Rinse off beer foam.
6.) Keep chilled, thereafter.
It's not perfect, but it allows one to safely defuse the bottle bombs, avoid potential injury to yourself and others, prevent further messes, all while saving most of the beer.