Buy as large a piece as you can afford. I hang a 12inch round gong at 300 and think it's just right. That's 4moa. It's big enough to catch most rounds fired at it and a can of any light colored paint works. You can see the hits thru a rifle scope and can see if you missed the wind call or otherwise wandered outside the standard one moa that the internet world always hits at any range.
It's heavy enough-3/8ths- that a 168 to 180 grain 7or 308 bullet won't swing it up over the hanger bar.
It's big enough to shoot groups on at 300, or to check your 300 yard impacts with a 200 yard zero, or to see where different loads from the same rifle land.
I hang a 21x24 plate at 800. Some days I need all of it to figure out the wind, and some days not.
There's a big difference between shooting a one moa group at 800, or even 300, and shooting a one moa group INSIDE a one moa target at those ranges.
