Bell indeed did use a bolt action for the vast majority of his hunting. Two of his favorites were the 6.5mm Mannlicher & the 7x57 Mauser which most folks do not consider Elephant rifles. As I recall he killed more than 500 Elephants with that little .276 (7x57). "IF" a critter is charging you are not concerned about Noise. If on the other hand, one is simply reloading after a shot with critters still present which it is undesirable to give away your location a bolt action can be worked softly & virtually Noiseless.

I do not have any of Bell's books but near the end of his life, he wrote an article in the American Rifleman with a summation of his years of experience in Africa. It was extremely interesting & I have re-read it several times. Bell hunted in a different time frame than did Taylor & both conditions & their technics were different.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra