To: Whom it may concern:

 November 3d, 1999

 GUN POWDER RESIDUE

 Gunpowder is made of a mixture of sulfur, charcoal, and saltpeter (potassium nitrite). It owes its explosive force to the fact that 1 mole of solid powder will when ignited produce 6 moles of gas. This rapid expansion in the enclosed space of a metal tube could be used to drive a projectile at high speed in a specified direction.

 Modern gunpowder is simply a refined version of the primitive substance in which the chemical composition has been altered to provide the greatest expansion with the smallest quantity and the least residue. The manufacture of modern powders is standardized enough that gunpowder residue can be analyzed by methods which identify specific components, which can aid the forensic scientist. 

Modern guns extract less unburned gunpowder residue then their predecessors. It is believed that about 15-16% of the gunpowder is not burned in the explosion and is ejected through the mechanism of the gun. With multiple shots fired by the same shooter one can expect to find more gunpowder residue then with a single shot fired.

 Modern guns have rifling or grooves and long “bore”.
Gun barrels grooves had originally been cut to reduce the problem of "fouling" from unburned powder residue. Thus, all modern weapons have "rifling" in their barrels.
This rifling is slightly different for each weapon, imparting different patterns of deformation on the bullet. These patterns can be used by the forensic scientist to aid
identification of a particular weapon used in a crime.

For gunpowder or shot pattern tests to have significance, it is essential to obtain ammunition identical in make, type, and age to that used at the crime scene. This duplicate ammunition is necessary for firing in the weapon in question to determine the distance of the muzzle of the weapon from the victim or other object at the time the questioned bullet was fired.

Gunshot residue is extremely fragile evidence and should be collected as soon as possible (preferably within three hours of the discharge of firearm). One should use the laboratory-supplied GSR kits and carefully follow the directions. In the case of live subjects, if more than six hours have passed or if the subject has washed his hands, it is unlikely that meaningful results will be obtained. If a body is to be sampled, whenever possible, gunshot residue collection should be performed prior to moving the body. If this is not possible, protect the hands with paper bags. Qualified lab technicians for gunpowder residue can later test the hands.

 The gunpowder does not ever burn with 100% efficiency in any kind of gun. It is known prior to 1963. This was all quantified by F.C. Barnes & R.A. Helson in their Empirical Study of Gun Powder Residue Patterns conducted in the late 50s to early 60s, and arose from and refers to even earlier tests conducted by Hatcher in the 1930s.
The specific cites can be found in the July1974 reprint from the Journal of Forensic Sciences, Volume 19, No.3.
The earliest copy of the study is contained in the Cartridges of the World, 4th edition copyrighted in 1965, page 367, paragraphs 1-8 of the summary and conclusion; which cites that "5-15%" of the gunpowder charge of any given load is discharged in the form of "UNBURNED & PARTIALLY BURNED" "PARTICLES or GRANULES" which can disperse in a pattern from 30 inches to over 8 feet.

 This article also cites British ordinance studies from the 1920s that qualifies the ways and means by which powder residue embeds itself into the pores of human skin; a fact that has been known since the earliest days of gunpowder use, probably going back to the first Chinese experiments in the 12th century A.D.

All of the modern powders predate 1963 by nearly 50 years, with 1915 being the date for the successful development of the "Progressive-Burning" powders as cited by Barnes & Helsey in paragraph 3, page 327 of the 4th Edition of Cartridges of the World.

From this then, we know that people involved in the discharge of firearms "WILL" acquire a certain amount of residue in the form of actual unburned and partially burned gunpowder embedded in the pores of their skin.

 Common sense and logic should dictate that a certain amount of this type of residue "WILL" also remain in and on the firearm itself.

 In fact, this is precisely the reason for cleaning the weapon after firing.

Finally, there are a numbers of reference texts that describe the various coatings used in the composition of gunpowder, the outer of which makes each granule nearly impervious to water which is why it can be washed out dried, collated and examined without degradation.

DuPont's Handloader's Guide to Gun Powder is one of the more comprehensive reference texts on the subject.

Liquid hot-wax can be used to lift gun powder residues embedded in the pores of skin. It is also known as Nitrate Test.
It has been known for centuries. References from both Hutton Webster and Will Durant indicate that this has been common knowledge from ancient times. One of the oldest direct reference to such is found on Page 218 of The People's Home Medical Library...published by the R.C.Barnum Co. 1916 which lists such things as usinghot-wax to remove the hair-fine cactus thorns from those incautious enough to sit in a patch of prickly pear.

The microscope has been perfected for several centuries and the science of micro-graphics and micro-spectroscopy has made analysis of the gun powder residues much more clear and comprehensive.

There is absolutely no reason why any gun, be it a rifle or a hand gun would not leave a residue on shooters arm, clothing, face, etc., short of the shooter being covered from head to toe.

 Charter Arms AR7 is not an exception.
Charter Arms AR7 is a survival rifle. When stowed, the AR-7 is only 16 ½" long... less than a foot and a half. It's ideal for backpackers, boaters, bush pilots... anyone who wants the security of a semi-automatic .22LR without lugging a heavy, full size rifle around. 

The AR-7's unique self-contained design lets it sit for months without attention. Yet when needed, it's ready to shoot at a moments notice.
Assembly is made quick and easy... without tools! Simply attach stock and barrel to action, feed the clip and fire!

Charter Arms AR7 uses standard high velocity .22LR rounds. Also features adjustable sights and convenient thumb safety.

 Accessories list includes: soft carrying case, collapsible stock, steel barrel, various round magazines, scope rings, a side scope mount plus a conversion kit.

 The rifle can be broken down into its major components and stored in the plastic stock. It islightweight and with only a .22 long rifle caliber, had virtually no recoil when fired.

This is a tedious little gun to put back together, but the internals of the receiver get real dirty real fast and a good cleaning is in order after every firing. It is worth mentioning that Charter Arms AR7 is a low accuracy gun known to jam and having firing pin problems.

 Specifications:  

Made by:AR-7 Industries, LLC
998 North Colony Road
Meriden, CT 06450
Tel: 203-630-3536
Fax: 203-630-3637

Respectfully, 

Boris S. de Korczak