Case Report #2: Use of BBs with Mesh Goggles (56K Warning!)

Case Report #2: Use of BBs with Mesh Goggles
(Created on 05/07/2008)

A) Purpose
Concerns have been raised that the use of biodegradable BBs is not recommended in conjunction with mesh goggles. Cases have been reported where bio BBs have hit mesh goggles and have shattered in many fragments penetrating the mesh surface and potentially injuring the operator.

In all those reported cases, though, it was never detailed what brand of bio BBs were used because it is obvious that different manufacturers use different mixtures and ingredients to fabricate their BBs. Patents have even been submitted to protect the company's secret “concoction” (see links in the reference section).

This report will compare the impact characteristics of conventional and biodegradable BBs on a piece of stamped steel mesh used for goggles. More BBs will be listed as they become available for testing.


B) Methodology
1. Gun
For this test, an upgraded ICS M4 gun will be used to fire point blank at zero distance to the steel mesh as measured from the muzzle.



The key configuration of the gun is listed below to ensure maximum repeatability in case another party wishes to conduct a similar test:
- ICS M120 spring
- ICS ball bearing metal spring guide
- G&P polyacetal piston
- Guarder polycarbonate ball bearing piston head
- ICS hop up with SytemA rubber sleeve
- SystemA 363mm tightbore barrel
- AEG Computer with integrated MOSFET and active braking

The gun is chronoed at ~400 FPS (0.2g TSD BBs) with hop up slightly engaged to simulate real-life shooting. At this point, it is not clear though, whether any rotation induced by the hop up would change the impact characteristics of the BBs.

It is important to mention that the AEG Computer has an active braking component, which ensures that the cycling process of the mechbox gears is nearly perfectly repeatable! This is especially crucial since normal AEGs tend to engage the piston even when a shooting cycle in semi-auto mode is completed. The reason for this is the stored rotational energy in the motor or “spinning momentum,” which needs to dissipate by spinning down against the resistance of the gears and its own internal magnet.

Here is a video that compares non-active versus active braking:
http://extreme-fire.com/Background/SW-SvsSW-AB.avi

From experience, a partially engaged piston might not give consistent FPS readings, and this would skew the test results.

2. Steel Mesh
The steel mesh for this test is the same that is used for mesh goggles produced by “Bitter End.” He provided this sample for me a while ago specifically for ballistic tests.



3. Setup
A metal tray covered with a black fabric will be used, on which the mesh sits. The tray will collect all scattering fragments, and the black fabric will make the BB debris more visible for photography.

BBs are loaded into a MAG mid-cap magazine. The gun will then be blank fired to make sure that BBs are loaded in the hop up chamber and gears are properly cycled. The gun is then placed directly onto the steel mesh and then fired again.

4. Results
The following BBs are listed in alphabetical order of their brand name and separated in regular and biodegradable BBs.

Regular BBs
AirSplat GID 0.2g:


=> Several tiny fragments are visible.


ECOBB 0.2g:

=> These BBs have NOT been tested because they pulverize on impact even after a distance of 60 feet!


Golden Ball 0.25g:


=> although these are cheap Chinese made BBs, they barely shatter in small pieces and are therefore pretty safe!


KSC Perfect BB 0.2g:


=> regarded as one of the best BBs on the market with an extremely slick and soapy-like surface, they appear to be pretty soft and shatter in a lot of pieces!


TSD 0.2g:


=> these are very safe BBs and simply split in half; you can even see the imprint of the mesh in the BB!


TSD 0.28g:


=> there are more smaller fragments than with its little 0.2g brother


Biodegradable BBs
AirSplat Bio 0.2g:


=> simply amazing impact characteristic for a bio BB!


TSD Bio 180 0.2g


=> only a few small fragments present


5. Discussion
In this test, only one round was fired, although one would argue that it would make more sense to fire more rounds and then average the results. There are two reasons why I did not pursue this concept: One is the lack of time, and two, these results represent a worst-case scenario. That means if a BB shatters only in a few fragments during this test, there is a good chance that in a real skirmish situation, it may not even break apart on impact. Our field rules require a minimum engagement distance of 20 feet, and the following chart (courtesy of "The Airsoft Trajectory Project) shows that a 0.2g BB fired at 1.49J (400 FPS) has already lost around 40% of its kinetic after only 20 feet, which corresponds to ~320 FPS:





C) Conclusion
It is amazing how well-constructed biodegradable BBs are compared to their regular brethen. I can conclude that it is safe to use biodegradable BBs with mesh googles if certain brands are avoided -- in this case it is "ECOBB" made by PaldoSports. The only obvious drawback of bio BBs at this point is their higher price.

A different article should discuss the viability of bio BBs when it comes to accuracy on the field.


D) References
Link to bio BB review:
http://www.airsoftmechanics.com/home/index2.php?option=com_content&task=view&id=14&pop=1&page=0&Itemid=29

http://www.arniesairsoft.co.uk/?filnavn=/articles/bio_tests/bio_tests.htm

New Bioval Bio BBs:
http://dedusa.com/news/?nid=3

A quick summary how bio BBs break down:
http://tcairsoft.com/forums/showthread.php?t=31

SW-Computer (“AEG Computer”):
http://extreme-fire.com/SW-COMPUTER.html

Bitter End Mesh Goggles:
http://www.st6-airsoft.com/mesh_goggles.htm

ATP - The Airsoft Trajectory Project
http://cybersloth.org/airsoft/trajectory/index.htm

Good Stuff

Lord Chaox wrote:

Good Stuff

Hey pal!

How's the weather in Texas? Any chance to shoot (with) your dad, yet *LOL*?

Jawz

Are theese new unopened packeges? I have a fealing at leaste some of theese bio bb's start to brake down as soon (or before?) you open the the bag. What about the ones left from "last weekend". I can't prove it, but I suspect my last failed piston was caused by thease same inferior bb's coming apart in the hop-up BEFORE they even leave the barrel, casing a jam and/or damage. When I cleared the jam, I got nuttin but peices! Mabey try the test again, using the same batch in a week or two. Might be interesting.

Andycapp wrote:

Are theese new unopened packeges? I have a fealing at leaste some of theese bio bb's start to brake down as soon (or before?) you open the the bag. What about the ones left from "last weekend". I can't prove it, but I suspect my last failed piston was caused by thease same inferior bb's coming apart in the hop-up BEFORE they even leave the barrel, casing a jam and/or damage. When I cleared the jam, I got nuttin but peices! Mabey try the test again, using the same batch in a week or two. Might be interesting.

You bring up a very good point! I actually mentioned in a different forum that I have placed AirSplat Bio BBs in a cup of water for about 4 weeks and have not seen any changes, which makes the definition of "biodegradable" a little bit iffy. But that's a different topic.

To answer your question: The AirSplat BBs are probably 4 months old and the TSD about 1 month. In this light, I am comfortable to say that those bio BBs have a pretty good shelf life, and as long as you keep them in a tight container, I don't see any problems with early degradation and therefore damage to your gun. This is a different issue with ECOBB BBs. They are also around 4 months old, but I would not use them in any of my guns anymore, let aside tightbore barrels! I only keep them for archiving purposes.

BTW, can you tell me what brand you used?

Jawz

Edit: I found the receipt for the AirSplat BBs (bought them at Big5) and it's dated back in Dec 2007 -- so that makes them 5 1/2 months old!!!

I t5hink they were the ecobb brand. What ever was available at sportco one sad sunday morning! Live and learn.

(PSA)
Plan ahead, and get down to Battlsim on saterday or before! Support your local retailer. It's worth the extra coin just have someplace you can go and get a hands on look at what you're buying. Not that the folks down in Oly seem to know what to do with it, but it's good to keep our hard earned dollers in our own economy.

I updated the test and added

Airsplat Bio 0.25g BBs.

Result: Awesome "stuff!" We finally have 0.25g BBs that are cost efficient and biodegradable!




Jawz

Addendum: Just for fun, I chronoed 16 shots with these BBs. FPS ranges from 366-371, mostly in the 368-369.