Ballistic gelatin
586066
222936580
2008-07-01T20:36:28Z
71.91.218.208
/* Uses */
{{Nofootnotes|article|date=February 2008}}
'''Ballistic gelatin''' is a solution of [[gelatin]] powder in [[water]]. Ballistic gelatin closely simulates the [[density]] and [[viscosity]] of human and animal [[muscle]] tissue, and is used as a standardized medium for testing the terminal performance of [[firearms]] [[ammunition]]. While ballistic gelatin does not model the structure of the body, including skin and bones, it works fairly well as an approximation of tissue and provides similar performance for most ballistics testing. Ballistic gelatin is used rather than actual muscle tissue due to the ability to carefully control the properties of the gelatin, which allows consistent and reliable comparison of [[terminal ballistics]].
== Preparation ==
The most commonly used formula: "10% ballistic gelin", is prepared by dissolving 1 part 250 [[Bloom (test)|bloom]] [[gelatin]] into 9 parts of warm water (by mass), mixing the water while pouring in the powdered gelatin. It is chilled to 4° [[Celsius]] (39° [[Fahrenheit]]). An older formula used by [[NATO]] among others specifies a 20% solution, chilled to 10° C (50° F), but that solution costs more to prepare as it uses twice the amount of gelatin. In either case, a 1988 research paper recommends that the water should not be heated above 40° C (104° F), as this can cause a significant change in the ballistic performance.<ref>{{cite journal|url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3177350&dopt=Abstract|title= Ordnance gelatin for ballistic studies. Detrimental effect of excess heat used in gelatin preparation|journal=Am J Forensic Med Pathol.|author=Fackler ML, Malinowski JA.|date=1988 Sep|volume=9|issue=3|pages=218–9}}</ref> For detailed preparation instructions, [[#External links|see below]].
To ensure accurate results, immediately prior to use, the gelatin block is "calibrated" by firing into it a standard .177 caliber (4.5 mm) [[steel]] BB, from an [[air gun]] over a [[gun chronograph]] into the gelatin, and the depth of penetration measured. While the exact calibration methods vary slightly, the calibration method used by the [[Immigration and Naturalization Service|INS]] National Firearms Unit is fairly typical. It requires a velocity of 600 ± 10 f/s (183 ± 3 m/s), and a BB penetration between 3.25 and 3.75 inches (8.3 to 9.5 cm). {{convert|600|ft/s|m/s|abbr=on}} is two to three times faster than the velocity of a BB propelled by a typical spring-air [[BB gun]], and so where a typical BB gun might not penetrate the elastic skin of an animal, the higher velocity calibration shot will penetrate the gelatin more than might be expected.
In his book ''Bullet Penetration'', ballistics expert Duncan MacPherson describes a method that can be used to compensate for ballistic gelatin that gives a BB penetration that is off by several centimeters (up to two inches) in either direction. MacPherson's Figure 5-2, Velocity Variation Correction to Measured BB Penetration Depth, can be used to make corrections to BB penetration depth when measured BB velocity is within ±10 m/s of 180 m/s. This method can also be used to compensate for error within the allowed tolerance, and [[normalize]] results of different tests, as it is standard practice to record the exact depth of the calibration BB's penetration.
==Uses==
Since ballistic gelatin mimics the properties of muscle tissue, it is the preferred medium for comparing the terminal performance of different expanding ammunition, such as [[hollow point bullet|hollow point]] and [[soft point bullet]]s. These bullets use the [[hydraulic]] pressure of the tissue or gelatin to expand in diameter, limiting penetration and increasing the tissue damage along their path. While the [[Hague Conventions (1899 and 1907)|Hague Convention]] restricts the use of such ammunition in warfare, it is commonly used by police and civilians in [[defensive weapon]]s, as well as police [[sniper]] and hostage-rescue teams, where rapid disabling of the target and minimal risk of overpenetration are required to reduce collateral damage.
Bullets intended for [[hunting]] are also commonly tested in ballistic gelatin. A bullet intended for use hunting small [[vermin]], such as [[prairie dog]]s, for example, needs to expand very quickly to have an effect before it exits the target, and must perform at higher velocities due to the use of lighter grain bullets in the cartridges. The same fast-expanding bullet used for prairie dogs would be considered inhumane for use on medium game animals like [[whitetail deer]], where deeper penetration is needed to reach vital organs and assure a quick kill.
The [[MythBusters]] team is also known to use ballistics gel in many of their experiments, but not necessarily involving bullets, including the [[MythBusters (season 1)#Episode_2_.E2.80.94_.22Cell_Phone_Destruction.2C_Silicone_Breasts.2C_CD-ROM_Shattering.22|exploding implants]] myth, the [[MythBusters (season 2)#Killer_Deck|deadly card throw]], and the [[MythBusters (season 2)#Ceiling_Fan_Decapitation|ceiling fan decapitation]]. They sometimes place real bones (from humans or pigs) or synthetic bones in the gel to simulate bone breaks as well.
==See also==
* [[Terminal ballistics]]
==Notes==
{{reflist|1}}
==References==
*{{Cite book|title=Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma|first=Duncan|last=MacPherson|year=1994|id=ISBN 0-9643577-0-4}}
*{{cite journal|url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3177350&dopt=Abstract|title= Ordnance gelatin for ballistic studies. Detrimental effect of excess heat used in gelatin preparation|journal=Am J Forensic Med Pathol.|author=Fackler ML, Malinowski JA.|date=1988 Sep|volume=9|issue=3|pages=218–9|accessdate=2008-02-23}}
*{{cite journal|url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15062946&query_hl=2&itool=pubmed_docsum| title= Preparing ballistic gelatine--review and proposal for a standard method|journal=Forensic Science International|author=Jussila J.|date=2004 May 10|volume=141|issue=2-3|pages=91–98|accessdate=2008-02-23|doi=10.1016/j.forsciint.2003.11.036}}
*[http://www.officer.com/publication/article.jsp?pubId=1&id=27983 Putting Bullets to the Test], Officer.com
*[http://www.firearmstactical.com/tacticalbriefs/volume4/number1/article412.htm 1998 INS testing procedure], detailing how ballistic gelatin is used to test service cartridges for a wide variety of situations.
*[http://www.firearmsid.com/Gelatin/Ballistic%20Gelatin%20Report.pdf INLDT Report: Ballistic Gelatin], [[Penn State]] Applied Research Laboratory
*[http://www.theoutdoorquest.com/perma-gel_ballistic_gelatin.htm A test of PERMA-GEL], a room temperature ballistic gelatin
==External links==
'''How to make your own Ballistics Gelatin.'''
* [http://www.recguns.com/Sources/XD3.html Rec.Guns newsgroup FAQ section on making ballistic gelatin]
* [http://www.tacticalworks.ca/content_nonsub/gelatin_testing/gelatin_preparation/ballistic_gelatin_preparation.html Ballistic Gelatin Preparation]
* [http://www.customcartridge.com/pdfs/BallisticGel.pdf Custom Cartridge, Inc. Instructions to make "Home-Made" Ballistics Gelatin]
* [http://www.myscienceproject.org/gelatin.html Make Your Own Ballistics Gel]
[[Category:Ballistics]]
[[Category:MythBusters]]
[[de:Ballistische Gelatine]]
[[pt:Gelatina balística]]
[[sv:Ballistisk gel]]