An interesting tid bit, for gun freaks is the story of how in the old days rattlesnakes used to get their heads blown off by a cowboy with a six gun.... remember? Well, that is actually truer than you think because the black powder guns were actually so much slower that shooting at a rattlesnake it would see the bullet coming and actually try to strike at it! That's why more actually had their heads really blown off! Smokeless was way to fast so it didn't give the snake the time to react to it and actually help it take off its head.
That story was told to me over fifty years ago by an old geezer in Arizona. We had shot some rattlers and the fellow observed our shooting and told us this yarn.
We tried to duplicate it, but could not. We photographed rattlesnakes striking, with me doing the photography and a friend of mine getting them to strike. We found that a shutter speed of 1/250 second would freeze the rattler in mid strike. A bullet could not be stopped by shutter speed, taking something like 1/10000 second to even get a blur. This with electronic flash.
After all this biologists told us rattlesnakes could not even see the bullet, they have very poor eyesight.
Incidentally, the muzzle velocity of blackpowder .45 Colt ammunition was just over 900 fps, slightly higher than the smokeless standard of 870 fps.