Any gun can fail proof . I have had personal experience of two guns failing through a cracked action ,one a Horsley sidelock and a very nice Pape thumb lever 16 bore which came back in several peices. I have also seen guns with a solid joint pin , the type with a bifricated cocking dog break the pin out due to the fact there was insuficiant metal to support it . That said it had lasted for 90 years or more but the shock of modern proof was too much .I have just gotten a 100 year old plus gun back from proof that I did have major resevations about the strength of the action , fortunatly it passed .
