Hello , gentlemen. I am new on these forums but definitely not new to big game hunting or fine fire arms. My Go to rifle for Dangerous African Game is my .450 Nitro Express Double rifle by Rigby. It is an excellent weapon for African Game. For the non dangerous game , l primarily use my Grandfather's 7 MM Rigby Mauser Bolt Action Rifle ( the one pictured in my profile ). For Fowl , l use a fixed choke Beretta 12 Bore Over Under shotgun accepting 2.75 inch cartridges. It's a pretty solid battery and has served me well , in my last safari. But l recently am Ordering a new Gun from Watson Brothers. It is a 4 Bore Droplock side by side shotgun , with double triggers and cylinder bores ( as in , Zero Choke in both barrels ) using 4 inch brass cases . I am having the gun built to fire Solid slugs / Round Balls. Here is the thing : The gun makers told me that a 4 bore slug fired from a Smoothbore will not have the penetration or stopping energy of a 4 bore rifle or a .577 NE or a .600 NE . But they still told me to ask around and see what other hunters say. So , l am asking anyone knowledgeable to answer me. Is a 4 bore slug/ round ball fired from a Smoothbore adequate to take down things like Cape buffalo ? Because if it isn't , then l wont use it for big game . Having shot Cape buffalo before , l know how vicious those things are , and l certainly don't wanna face off an angry brute like that with an underpowered gun . My .450 has always put them down easily. I know that in the old days many hunters used 4 bores , but these were mostly rifled . Only two people used Smoothbores of 4 gauge . One was FC sealous who used 4 bore percussion Hollis and Sons Duck guns loaded with Ball and a handful of black powder . The other was George P Sanderson who used a WW Greener 4 bore cartridge ball gun. What do you experienced gentlemen think ?