The only 2 double barreled rifle calibres which do not ( appear to ) have a ballistic counterpart in a bolt rifle are the .577 Nitro Express ( propelling a 750 grain bullet ) and the .600 Nitro Express ( burning a 900 grain bullet ) .
Below , is a photograph kindly lent to me by my good friend , former colleague and fellow forum member , Sergeant Kawshik Rahman taken by him in an auction house in Sirguja in the late 1950s . It is a .600 Nitro Express double barreled rifle , built by the British company , Holland & Holland for His Royal Excellence , the Maharajah of Sirguja during the British Colonial era.
