Candidate 4: Ultimate BB 0.20g

The Ultimate BB, manufactured from high-density polyethylene (HDPE) came packaged in a sealed paper carton, indicating sensitivity to photodegredation, similar to HDPE garbage bags. According to The 6mm Shop, these BBs will rapidly degrade within 4 to 6 weeks, requiring careful storage away from light and moisture. The BBs displayed excellent diameter consistency, supporting the claim on the package stating: "100% guaranteed to be 5.98mm." Our measurements show an average of 5.97mm with a scant standard deviation of .007mm. The UBB surface was slightly rough and appears to have slight blemishes throughout. This may have contributed to the below average roundness consistency numbers.