Works as well as holding three cartridges in the web or between the fingers of your front (forend) hand. I have never gotten as fast as a semiautomatic can run but shooting beside a bolt action firearm I am not slower. But it is an interesting device.
I could hold second shell in my mouth and put into chamber and then shut gun and fire. That trick ended when i shut the gun on my lower lip. Thank God not pull trigger. That ended that trick shot i assure you.