Case Report #2: Use of BBs with Mesh Goggles(Created on 05/07/2008)
A) PurposeConcerns 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) Methodology1. GunFor 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.aviFrom experience, a partially engaged piston might not give consistent FPS readings, and this would skew the test results.
2. Steel MeshThe 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. SetupA 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. ResultsThe following BBs are listed in alphabetical order of their brand name and separated in regular and biodegradable BBs.
Regular BBsAirSplat 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 BBsAirSplat Bio 0.2g:
=> simply amazing impact characteristic for a bio BB!
TSD Bio 180 0.2g
=> only a few small fragments present
5. DiscussionIn 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) ConclusionIt 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) ReferencesLink to bio BB review:
http://www.airsoftmechanics.com/home/index2.php?option=com_content&task=view&id=14&pop=1&page=0&Itemid=29http://www.arniesairsoft.co.uk/?filnavn=/articles/bio_tests/bio_tests.htmNew Bioval Bio BBs:
http://dedusa.com/news/?nid=3A quick summary how bio BBs break down:
http://tcairsoft.com/forums/showthread.php?t=31SW-Computer (“AEG Computer”):
http://extreme-fire.com/SW-COMPUTER.htmlBitter End Mesh Goggles:
http://www.st6-airsoft.com/mesh_goggles.htmATP - The Airsoft Trajectory Project
http://cybersloth.org/airsoft/trajectory/index.htm