I've been testing a fair bit with my 9,3x74R. The .470 already had a Good handload when I bought it.

I usually have two targets close to each other - fire right barrel on the right target and left barrel on the left target. Short time between shots, just the time I need to put in a Good next shot.

Then I usually shoot some other rifle to let it cool off. The way I see it the DR is for two Quick shots. If you need no 3-4-5-6 it is probably at very short range and you're in a hurry? I reckon it doesn't matter so much then. If it's on the spot on the two first shots, they're usually not so much off on the other shots in practical terms.

Anyway, pistoltargets with 4" bulls is what I use at 50-75m range. They aren't wider apart than I can shoot over the Chrony at the same time.

Put one target on top of the other and mark through the hole with a pen - a fine printed target! Do it again for 3+4 and 5+6.

That way I can measure the precision of each barrel essy without too much fuss.