Actually a simple solution, maybe, would be to find a double barrel action THAT HAD NEVER BEEN BARRELLED. According to ATF as long as it never had been barrelled, you can make a pistol out of it. Many of the early silohuette (sp?) shooters in my area tried taking MK X mauser actions and making handguns out of them. Some were successful, some were not. Anyway, how about a 10" barrelled .600 Nitro double pistol....you first....