Good question Melvin, I can share what I do maybe it would help. I guess first make sure, if possible, you have a good tune, good barrel maintainence, a proper platform to evaluate 1 thing not 12 things. I personally start with machine preference and over the last few years I've probably shot them all, the last couple only a single machine and all guns seem to be happy with it. This part is hard and you simply have to try lots of stuff. I've determined for me, I'm looking for a speed range within maybe 6-8 fps. I'm sure I miss stuff but it works and keeps the variables controllable. Once I get ammo I really try and be patient as to a weather window decent enough to evaluate. Like most I start with groups, usually 5 shot groups and the best stuff out there should put most in small round holes maybe cut it a bit. I'll shoot some groups, start right after shooting a card, if I get anything weird I'll shoot several more right then just to see if it was me or ammo. Honestly, after a while you just get a feeling that this stuff is A-list or OK maybe use it in local matches or sell it off a couple bucks less than cost and believe me I've sold plenty od decent stuff off just because I found something incrementaly better. The last test is match shooting, if new stuff does anything at all wild, I'll never use it in an important gun, you know those droppers are out there someplace you just gotta keep trying to narrow the odds. Anyway this seems to work for me at least.