How to measure bb quality without using high tech machines:
1. Try to grab one bb. If it is hard to get, that means that it is highly polished.
2. Get a hammer and lightly tap the bbs to split it in half. If there are bubbles, make sure to see where it is located. The more centered it is the better. Obviously no bubbles is the best.
3. Look at the bb under a magnifying glass, There should be no seams or spare pieces of plastic attached to the bbs. Also check for pits.
4. Look at the color. (this only works with the white bbs) If there are black or gray speckles, there might be some imbalance inside the bbs.
5. Brands. Just look around the forum to see what bbs most people are using.
There is another method about 6mm BB's;
You from the following aspects to test:
1) Diameter = 5.95m+/-0.01
2) Perfect sphere shape & smooth surface;
3) Made of high strength/tough materials;
4) No external pitting on the BB;
5) Seamless (no visible seams);
6) No visible internal air bubbles/pits;
7) Significantly stable flight characteristics,less drift by wind & shoot straighteners;
Is True Biodegradable material
You can choose suit bio BBs for your bbgun.
Recommended brands: BulletBalls(China mainland) MADBULL Goldenball etc.