I've been doing some comparisons of the bio BBs I have over the past week or so as well - ASG Open Blasters, BioSphere, Nuprol RZR Bio, all in 0.2 & 0.25g.
On paper these should be identical - they're all supposed to be 5.95mm with 0.01mm tolerance either way - and while they all perform adequately enough at 0.2g in my experience from shooting them prior to the lockdown the ASG Open Blasters seemed to the best of the three, and the Nuprols had a habit of double-feeding sometimes. I haven't used the .25g BBs enough to have any idea which of those three shoots the best though.
20 of each BB were weighed and measured and they were broken apart to check for air bubbles. When measuring a BB's diameter I rotated it and re-measured to check the variation in diameter around it & get an idea of its "roundness", noting the min, max and average diameter.
Some were measured then soaked some in water for >24h (was generally around 40h-ish) and then re-measured to check for any swelling due to water absorption.
There are some caveats to keep in mind:
- The scales I used only have a 0.01g resolution which isn't really precise enough (and they're cheap, so they're not exactly top quality either) however they should at least be sufficient to show up any significant discrepancies between the specified weight and actual weight. They're also sensitive enough that things like airflow around them can skew the result. To attempt to compensate for these to some extent I weighed each BB repeatedly and used the most frequent result.
- Similarly, my digital calipers (Facom 1300EA) have a resolution of 0.01mm so borderline values might read either way, but again this should be enough to show any significant variation at least.
- Just because I didn't find any air bubbles in a BB doesn't necessarily mean that there weren't any; there could have been some in the parts of the BB that were not exposed or they may have been too small to see with the naked eye.
- Also, 20 BBs is a small sample size
So this isn't exactly a rigorous, in-depth look & you shouldn't take the results as entirely accurate. Also they're likely to vary from batch to batch, with some being better or worse than others. But it should at least provide some interesting information & comparison between these three brands of BB beyond merely shooting with them
Nuprol RZR Bio 0.20g:
Weight: Typically 0.20g, 3 measured 0.21g
Size range: 5.92 - 5.95mm; 11 measured within tolerance.
Roundness: 13 measured with max variation of up to 0.01mm, 4 with 0.02mm, 3 with 0.03mm
There was no sign of swelling after soaking in water.
Nuprol's BBs have a consistent weight but their measured size was outside of specification on almost half of the BBs tested - minimum measurements of 5.93mm were not uncommon and a few were even as low as 5.92mm. None measured above 5.95mm.
They are relatively soft though - I had to be very careful when measuring their size & shape as it was very easy to read lower measurements even with the small amount of force applied by the calipers.
I did not see any bubbles inside any of the BBs tested.
BioSphere 0.20g:
Weight: Typically 0.20g, 6 measured 0.19g
Size range: 5.94 - 5.96mm; all measured within tolerance.
Roundness: All measured with max variation of up to 0.01mm (15 did not vary to an extent I could measure with my calipers)
There was no sign of swelling after soaking in water.
BioSphere's BBs are quite consistent in weight (trending more towards the lighter side) and impressively consistent in size/shape, measuring 5.94-5.96mm with no more than 0.01mm variation in diameter around any given BB - all within the specified 5.95 +/- 0.01mm tolerance.
They readily split into fragments when crushed, and unfortunately I found a bubble in every BB I tested. Here's a photo of one that I managed to crack open more or less cleanly showing the air bubble:
View attachment 57565
ASG Open Blaster 0.20g:
Weight: All measured 0.20g
Size range: 5.90 - 5.96mm; 6 measured within tolerance.
Roundness: 9 measured with max variation of up to 0.01mm, 7 with 0.02mm, 3 with 0.03mm, 1 with 0.04mm
There was no sign of swelling after soaking in water.
The Open Blasters had a very consistent weight with all of them measuring 0.2g, but their size and shape varied to a greater extent than the Nuprols, from 5.90mm to 5.96mm. One of the BBs tested varied between 5.92 and 5.96mm!
They seem to be of a similar material as the Nuprol BBs but a lot harder. I did not see any bubbles in any of the BBs tested.
Nuprol RZR Bio 0.25g:
Weight: All measured 0.25g
Size range: 5.91 - 5.95mm; 3 measured within tolerance.
Roundness: 15 measured with max variation of up to 0.01mm, 3 with 0.02mm, 2 with 0.03mm
There was no sign of swelling after soaking in water.
Unsurprisingly these are much like the 0.2g version - their weight is quite consistent while their size and shape is about as variable, though they seem to be a bit smaller on average and a couple measured as low as 5.91mm.
The 0.25g Nuprol RZR Bio BBs are significantly harder than the 0.20g version and didn't deform so readily. I did not see any bubbles inside any of the BBs tested.
BioSphere 0.25g:
Weight: Typically 0.25g, 9 measured 0.24g
Size range: 5.93 - 5.94mm; 16 measured within tolerance.
Roundness: All measured with max variation of up to 0.01mm (17 did not vary to an extent I could measure with my calipers)
There was no sign of swelling after soaking in water.
These varied a bit more in weight than their 0.2g version, and like their 0.2g version trended towards the lighter side. Their size and shape was very consistent too with none varying by more than 0.01mm, although they were slightly smaller than the 0.2g version with all of them measuring between 5.93mm and 5.94mm.
Unfortunately, just like the 0.2g version I found an air bubble in every one of these I inspected too. These were also much harder than the 0.2g version and they had a tendency to shatter suddenly once they started to crack but I did manage to break open cleanly for a photo:
View attachment 57566
ASG Open Blaster 0.25g:
Weight: Typically 0.25g, 6 measured 0.26g
Size range: 5.90 - 5.95mm; 1 measured within tolerance.
Roundness: 13 measured with max variation of up to 0.01mm, 4 with 0.02mm, 2 with 0.03mm, 1 with 0.05mm
There was no sign of swelling after soaking in water.
These seem to be slightly less consistent in weight than their 0.20g version, trending slightly towards the heavier side. Their size & shape is about as variable, ranging from 5.90 to 5.95mm and like the others these also trend slightly towards the smaller side.
I did not see any bubbles inside any of the BBs tested.
It makes me wonder how biodegradable these Bio BBs really are.
I suspect that manufacturers realised that true bios had swelling problems from absorbing moisture in the air etc so they changed the formula to be higher percentage plastic or whatever the composition is.
So now they're probably no more degradable than normal BBs
Next test would be to bury 10 or each for a year and then compare them
As I posted earlier in this thread, AFAIK most are made from
PLA & as such I wouldn't expect them to biodegrade very quickly in the environment.