I recently purchased a Sig 556 Swat with a twist rate of 1:7 IIRC. Looking for opinions of those that have this rifle as far as what brands of ammo and bullet weights that your rifle likes. Should help me narrow it down a bit without having to try them all

Mine was accurate with just about anytihing, but it's favorite was 68gr Black Hills HP.

Almost every rifle has it's own preferences.

I had a friend years ago with two rifles, same manufacturer, literally only a few serial numbers away, and one rifle shot great with one ammo and terribly with another ammo.  The second gun shot great with ammo #2, but terribly with the first ammo.  All depends on the barrel.  Anyone who tells you that so-and-so ammo will do "best" in your rifle is giving you poor info...you have to test them all...and your rifle will shoot some better than others.

I can usually find an ammo that will shoot 2" or less if I do enough of a search for ammo...

my 556 swat is excellent with prvi partisan match.