Recall that:
BBBastard wrote:... There is an engineering "wall" where beyond 0.28 grams in this formula [PLA], where less fibreglass (binder) is added and more PLA and the material also undergoes compresson in the mold. This results in a poor bond and the BB is weak and prone to breaking apart when exposed to firing torque forces. Not just on impact, but in the violent feedpath (mag to end of barrel has high speed directional changes of up to 90 degrees) of an AEG itself. This can cause damage to the firing platform (torn hopups, jams and fine powder in the device).
Adding Weight
Airsoft BBs need to be 5.95mm, + or -0.01mm. Larger BBs will not feed properly and smaller BBs have poor feeding and flight characteristics. This creates an engineering problem when a BB needs to be a weight higher than 100% within the target diameter. PLA material is required to reach that weight.
Many manufacturers have resorted to "doping" to overcome this. Doping adds weight to a BB by adding a heavy material. The problem with doping is twofold:Doping additives result in a heavier BB, but also result in a formula that is not considered "non-toxic".
- ... Weight additives with less fibreglass introduce a heterogenous thermoplastic base that causes the BB to be "brittle". ...
- ... add substances such as Zinc Oxide to bring the weight up. ...Zinc Oxide is a metal and is not considered bio-friendly. Found in soil, it is considered and industrial contaminant
...
In Canada, soil analysis is a mandatory step in the land sales process. Remediation will be ordered by the Ministry of Environment and the owner will pay for that expensive process -- sometimes costing more than the land value itself. And once it is found, remediation is required, the landowner cannot simply withdraw from the sale of the land.
Detecting Doping
... Doping is NOT an advisable practice, and it defeats the ecological goals of a BIO BB, even though the BB retains it[sic] characteristic breakdown attributes.
... Once a BIO BB reaches 0.28g, the need to dope for weight to go beyond that weight becomes an engineering necessity. Compression of PLA and fiberglass can be used up to 0.32 grams, but the BB quality suffers terribly. Beyond 0.32 grams, doping in a BIO BB is assured to reach a target weight.
... Mass spectrometry has shown unidentified metal spikes in the material of others, showing metal doping is a common practice in heavyweight BB production today.
Emphasis added.
( https://bbbastard.com/media/promo/BBBas ... on2014.pdf )