I'm just gonna copy/paste a few of my own comments on another forum discussion surrounding these silicon BB's:
Although I have not shot or tested these BB's myself, I do not allow them at my games based on the bit of online research I've done. My concern is that it is reported that these BB's can shatter/break glass much easier than regular BB's. The theory makes sense to me - image throwing a steel bearing and a rubber bouncy ball at a plate of glass and guess which one you assume to break the glass easier.
Here's the nerdy explanation for those curious:
It's claimed that ceramic BB's transfer LESS energy on impact because they do not deform as much as plastic ones - this is their argument as being MORE safe than plastic BB's. I don't fully understand the physics here but they may have a legit argument. I believe this is a moot point on soft objects (such as people) and the energy transfer would be similar.
The problem I see is that because ceramic BB's do not deform, on impact with glass the force is concentrated (like using a ballpeen hammer). Brittle materials, like glass, have virtually no "give" to them so when they reach their yield stress they fail/break. Unlike ductile materials like steel where they will deform and bend after they have reached their yield strength but may not necessarily fail/break.
Conclusion: Even though (arguably) ceramic BB's may transfer less energy than plastic BB's, the concentrated stress they apply will be greater than plastic BB's, which is why I believe they have the greater potential to break glass over plastic BB's.
My other concern would be I believe they would be more likely to shatter/chip teeth, but that's strictly a guess.
My conclusion (I'm a mechanical engineer):
- Soft tissue damage is probably a negligible issue
- Damage to hard surfaces such as windows and teeth should be be the focus of concern.
Kokanees pictures of the lense in the OP verify a couple very important points:
- We cannot conclusively say that regular BB's transfered more or less energy than the silicon BB's. People need to stop thinking about "energy"; it's too complicated for most people to understand fully - including myself - and it varies between different interacting materials.
- We CAN conclusively say that the harder silicon BB's caused a much higher stress on the lens - this is PROVEN by the permanent deformation of the lense. To get get permanent deformation on a material (assuming it's a ductile material), the material needs to be stressed PASSED the yield strength of the material, which is what did NOT occur with the regular BB's and DID occur with the silicon BB's. Note that brittle materials, such as glass, generally won't have permanent deformation...they just fail/break once the yield strength is reached.
Hope that helps. I recently was given some BBmax samples so I'll be doing my own indipendant testing on them to see how they interact with impacting different surfaces. I don't allow them to be used at games I host based on my knowledge currently...I'd rather error on the side of caution for now.
EDIT: Someone should pull the ASME Z28.1 (IIRC) standard. I remember reading it a while back and I believe the testing was done using a steel projectile and XXX velocity. So I don't suspect eyewear to be a concern if they meet the proper standard certification.