Here is a target fired with tumbled ammunition---not .303, because I don't have any ugly enough to tumble.
This is 1970's WCC .223 recovered from the ground somewhere in Central America, tumbled to make it pretty and then sold to suckers in the USAicon. (I got it cheap from an estate sale, before you jump to any conclusions.)
Just standard 55grain FMJ, fired from an Eagle Arms A2 H-Bar, using standard A2 iron sights, rested on sandbags.
Rate was "semi-rapid", which involves minimal sight alignment and a little less speed than a you-tube mag dump.

Notice the wild dispersion of hits caused by the degraded nature of the tumbled ammunition. Pressure must have been all over the place, too, as I could see the sides of the receiver puffing in and out during the course of the string.
Finally, the rifle blew up and I died.
A needless tragedy.
-----krinko