I have a Merkel 140 in 9,3x74R - it has a set front trigger and if you want to double it on purose you need to set the front trigger and pull the rear trigger - it will double every time.

I did it on purpose just to see what happens once

- no toticable delay between shots just one big "ka-boom" - with my left (I am lefty) middle finger swollen and a sore cheek - distance 3m ~ 10 feet - black circle dia is 3 inches:

BTW - could we compare terminal balistics between such a doubling (just in theory) of 9,3 cal with a single shot from one of 450's (energy, KD effect...)?