You guys are over thinking this. All it needs is 50 rounds of .27 BBMax for the test, 50 rounds of .28g white plastic bbs for the control, and maybe 50 rounds of .2g white bbs for a baseline, and some goggles to shoot at varying distances, say 10 rounds of each at each distance. Technically new goggles should be used for each set of 10, to ensure they haven't already been weakened by the previous 40 rounds, but even using the same goggles would provide better insight than no test at all. To perform the best safety test, the minimum range should probably be 1 foot, to simulate an accidental discharge at point blank, and the max should be outside the MED for the rifle (which should be <400fps).
My hypothesis, is that none of them will break ballistic goggles, and all of them will break safety glasses at close enough range.
I would like to see all shot @ the same spot,40+ rounds point blank (worst case and least varibuls), with 2.8J+ might as well throw in some .4s so it covers all the baces
the question @ hand is does polycarbonate act hard or soft.. it "should" be soft. the question in my mind is there a difference in mutipul shots w/BBMAX causing more cracking and faster failure, because it does fail threw cracking
over all (with in normal power limits) you should not see a single shot failure, even with .177 steel.
Ahh, good point, I was thinking backwards on the density, so now about the impact area and energy distribution, does increased distance reduce the penetration, and if so how much distance is required at various fps to reduce it to within the safe zone?
I'm off to scour the interwebs again for the answer if I can find it.
that i can give you
"safe" is some were below 1.36J. go to http://mackila.com/airsoft/ATP/
to find out @ what point what bb slows @ what muzzle engery..
rember "penetration" realy only aplys to hard surfaces.. on soft a .27 is a .27.. not much of a diffrance..
"There is a common myth that because an airsoft BB is light, plastic, round or something it is magicly not dangers whn compared to airguns of similar engery out puts. This is simply not true, with the obivus exception that is becomes less dangurs @ range faster.
Fact of the matter the difference in relative penetration of ballistic gelatin by airgun pellets and airsoft BBs is 0.01 joules” http://www.ukasgb.org.uk/ukasgb_guidelines_v3.pdf
How can this be true? It has to do with the fact the FPS in a big componet of soft tissue pentreation
In "Wound Ballistics" by Coates and Bayer (1962 ). “On pages 138 and 139, they discuss the issue of skin penetration. They used 1/8 inch steel spheres weighing 2 grains(.129g). The target material was human skin and the threshold velocity was 170 fps(.12 J). When they substituted 1/8 inch lead spheres weighing 7 grains(.453g) they did not achieve penetration at 161 fps(.54 J)” http://yarchive.net/gun/ammo/wound_ballistics.html
it clearly shows FPS effect on penetration as projectile with 4.5X the muzzle energy of another one of the same size failed to penetrate do to being 9fps slower. See Annex 1 for a simple airsoft based demonstration of this effect.
So the next time you handle your 2.8J rifle treat it like you are shooting a .177 lead pellets @ 343 fps.
9 A 3.9 J rifle ( 650 fps) is Not“safe” to use
Airsoft sniping, how much power is too much?
Short answer, anything more then 2.8 joules (550 w/.2s), Muzzle energy on the field should never be beyond the rating of the eye protection. ANIZ78+ High Impact goggles are rated to 2.89J. No MED arguments, accidents happen. People have and will be shot point blank when it happens we don’t need a loss of an eye or worse
its probably lower than 2.8J, some were between 1.35 and 2.8 joules you cross the line form toy to a wepon that has the abilty to create a leathel would , I am not going to cross the line and tell people what is safe, I will just focus on a level I can prove is UNSAFE.
1.35 J can cause a BB to stick in the skin, . @ the point a BB sticks in and need to be popped out its is deeper then 3mm, far enough to reach a few major blood vessels. Of note UK law puts 1.35j as leathal force
3J is proven to be well with in the lethal range
Pay attention to the facts for a .22 projectile as 5.88mm is close enough to our 6mm BBs to draw conclude as to what an airsoft bb will do.
Vincent DiMaio’s 1989 paper “Minimal Velocities Necessary for Perforation of Skin by Air Pellets and Bullets, Journal of Forensic Sciences" referenced below is the standard on small projectile penetration. While reading this keep in mind FPS is a BIG contribution factor to penetration, in general a faster lighter projectile will have more skin penetration then a hever slower one of the same cross section and impact engery.
While DiMaio used pellets, studies have shown a round ball to have more penetration. http://www.pyramydair.com/site/articles/pellets-vs-round-balls/
The FPS and shape factors both give a airsoft bb a lower Joule penetration threshold, (not a higher one as one would assume) then DiMaio’s .22 cal pellet results. This can be seen in real world results
1) Medical records, have shown .177 BBs (.345 gram)
@ 290 FPS(1.34J) pentrate the skin
@ 331 FPS (1.77J) complete passage through the skin and into soft tissues
@350 fps (1.95J) pentrate deep in to tissue http://www.protecteyes.org/small_projectiles.pdf http://www.cpsc.gov/LIBRARY/FOIA/meetings/mtg04/gun.pdfhttp://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1334215
2) Field experience and player reports has shown impacts form a BB around 380fps (1.35J) and above (remember a .2 drops form 400 to 300 in 20 ft, so we are talking darn near point blanked with a 1.5 J gun(400 w/.2s) has caused BBs to lodge in the skin. http://sequoiaairsoft.com/img/bbdamage2.jpg
3) 1.35 joule, the UK cut off point for “lethal” . In testing a 1.36 J .2g airsoft bb will penetrated ballistic gel http://www.ukasgb.org.uk/fcc_response.pdf
This is an important fact as even “simunition” doesn’t penetrate ballistic gel. http://www.simunition.com/upload/fichier_4.pdf
so any one notice the number 1.35J -+.01 keeps poping up??
Following quotes Taken from
FIREARMS CONSULTATIVE COMMITTEE
ELEVENTH ANNUAL REPORThttp://www.archive2.official-documents.co.uk/document/deps/hc/hc501/hc501.pdf
“there are areas on the human body
where vulnerable blood vessels lie 3-5 millimeters below the surface
the skin, an injury to which could result in death. Consequently, any
projectile capable of penetrating skin and underlying tissues to a depth
of 3-5 millimeters (less than the length of many pellets) could cause a
potentially lethal injury.”
Think about get shot in the radial arty (wrist) or carotid (neck) , any were you can take a pulse is with in range
“For our purposes, however, the paper
by Di Maio (et. al.)4 is perhaps the most helpful in defining the
threshold velocity for the penetration of human skin using as they did,
surgically removed legs for their test medium rather than other animal
tissue or tissue stimulant. They determined that a “domed”5, 0.177
pellet weighing 8.25 grains would penetrate skin at a velocity of
290 f/s (KE 1.54 ft lbs. or 2.08J, while a similar 0.22 pellet weighing
16.5 grains did so at 223 f/s (KE 1.79 ft lbs. or 2.42J).”
“Di Maio and his colleagues also determined the velocities at
which pellets would “perforate” skin, which they defined as passing
completely through the skin and into the underlying soft tissues. They
determined that for perforation, a velocity of 331 f/s was required for a
0.177 pellet (KE 2.0 ft lbs. or 2.71J) and 245 f/s for a 0.22 pellet (KE
2.16 ft lbs. or 2.92J)”
"26. The Home Office and the Forensic Science Service considers that the lowest level of muzzle energy capable of inflicting a penetrating wound is one foot pound force (1.35 J): below these power levels, weapons are "incapable of penetrating even vulnerable parts of the body, such as the eye". However, more recent analysis by the Forensic Science Agency for Northern Ireland has indicated that a more reasonable assessment of the minimum muzzle energy required to inflict a penetrating wound lies between 2.2 and 3.0 ft•lbf (3 to 4 J). We will deal more fully with this discrepancy at paragraphs 123 to 130 below."
"123. The power level at and above which an air weapon is considered a firearm in law is presently set at 1 ft•lbf. However, we note above that the Forensic Science Agency of Northern Ireland has more recently assessed the power level at which a barreled weapon is capable of inflicting a lethal wound as between 2.2 and 3 ft•lbf, and the Secretary of State for Northern Ireland has proposed that the law relating to firearms in Northern Ireland be amended to take this into account."