I bought a box of .222 winchester brass, about 500 pieces. I have it about 2/3 sorted and am matching up groups of .3 grains. When I am done I will measure case neck thickness and turn if needed, along with primer pocket uniforming and flash hole debur. Any advise on how much weight spread would be ideal. I was thinking .5-.6 grain would be good enough. I am doing this to get a group of 100 or so pieces of good brass for our state games in a for score, 200 yd bench rest meet. The rifle is a Sako L-46 in the factory lightweight class. I tried for the Lapua brass but it won't be ready for delivery until summer.

You can graph the weights with Excel.
This can help you sort it. I like to throw out the highs and lows and use what is left in the middle or just sell the highs and lows or use the heavy cases to work up your loads.

One thing to keep in mind though. Brass has 8X the specific gravity of most powders. A one grain powder charge variation takes up as much space in the case as 8 grains of brass. If you are happy with ± .2 grain charge variations you should be happy with 8X that much in case weight variations.

is it new brass or once fired?
with a factory rifle ,factory chamber, you need some where to start i try to keep my spread inside .5grs . on weight.. If you are trying for 100 good pieces for a match you may not get it with 500 cases. I would try and get 120 cases 20 to use to work up a load..with new brass for a match I will check trim all brass to exact length, clean and champer the inside out necks and then turn the necks to about 95% or better just enough to make sure the necks are all sane wall thickness. fire form the brass with a moderate to stout load so it fully forms to the chamber.
take 20 cases partial neck size only and work up a load, once you have a load worked up load the 100 cases. a full case of powder will be between 24 and 27 grs. you could check the cases for volume using a fine ball powder, that would give better results than weighing cases.
Dave

I got 99 cases within .2 grain and 260 within .5 grain. It sounds like I should take those and measure neck thickness, to check case consistency, then neck turn the best cases, fire form and then check case capacity. Lots of good advice guys. I think when I am done, I will compare those groups to the cases with extreme weight spread and see if I wasted my time! FYI, after all of this Graf shows Lapua .222 in stock. I may compare Lapua to the sorted and preped WW also.

prep all your brass befor you sort.. lapua in most cases is a little better brass. i have some 243 though that was not as good as say winchester. its tough to compare because the conditions are always changing.
what works for me is after I have worked up the best load possible any rounds fired that are outside the normal group for a five round group go into diffrent lots
that case will be put into a new or diffrent batch of cases with the same outcome.
if the round is to the left it has its own lot if it goes right then another and so on..