Just after I started shooting I was listening to a couple of the old(er) timers bitching about their recent poor performance. One of them blamed the ammunition they were using. The other pointed out that while shooters often blame the grade or particular batch of ammunition, nobody ever credits their ammo when they shoot a particularly good card.
You might not think that your choice of ammunition would make such a difference. Pretty much like pipette tips, you might say, within limits a bullet is a bullet. I mean, yes, you’ve got your tips that come in bags so that you have to contaminate them yourself when you rack and autoclave them and you’ve got your ordinary racked tips and your plugged RNAse-free tips and tips that were packed by the lily-white fingers of virgins brought up on a diet of organic fava beans on a Pacific island, but essentially a pipette tip is a pipette tip. Except for the ones that stay on the Gilson just long enough for you to suck up 37.5 µl of incredibly rare primary antibody only to fall off halfway between one Eppendorf tube and the next, sending 5 years’ work down the drain but hey, never mind we get cheap tips because the lab tech is shagging the sales rep.
I mean, you’ve even got different calibres. 10 µl, 200 μl, 1 ml, 5 ml: that could almost be .22, .308, .38 Special and 50 cal.
Anyway, there are differences in quality of ammunition (or so the manufacturer claims) and as ever, you get what you pay for.