Journal of Criminal Law and Criminology

Volume 61 | Issue 1 Article 12

1970

Zip Guns and Crude Coversions--IdentifyingCharacteristics and ProblemsBruce Barak Koffler

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Recommended CitationBruce Barak Koffler, Zip Guns and Crude Coversions--Identifying Characteristics and Problems, 61 J. Crim. L. Criminology & PoliceSci. 115 (1970)

THE Jounz;mw or Csnnxri, LAW, C-NOLOY AND POLICE SCIENCE Vol. 61, No. ICopyright @ 1970 by Northwestern University School of Law Printed in U.S.A.

ZIP GUNS AND CRUDE COVERSIONS-IDENTIFYING

CHARACTERISTICS AND PROBLEMS

BRUCE BARAK KOFFLER

This is the second part of Bruce Barak Koffier's article. Part one appeared in the December,1969 issue. Mr. Koffier is pursuing graduate studies in criminology at the Center of Criminology,Ottawa University, Ottawa, Ontario, Canada. He holds a B.S. degree from Trenton Universityand serves as a firearms instructor for the Government of Ontario.-EDrroR.

Conversions

CAP-FInRNG PISTOLS

The toy cap pistol represents an advance overthe crude zip gun because it already has the entireaction and needs only minor modifications to makeit fire a .22 rirmfire cartridge. The gun is usually alight metal casting held together by rivets throughthe grip, cylinder, and barrel. By removing thebarrel rivet and inserting a piece of car radioantenna, taping the original barrel so that itfirmly holds the tubing in place and providing afiring pin, one has a weapon capable of firing liveammunition. If the tubing does not fit tightlyenough, it may have to be soldered into position.A firing pin may be added to the hammer by drill-ing a small hole through it and screwing in a self-tapping screw. Some weapons examined in NewYork City simply had the face of the hammer filedto a crude point. If the shooter finds that his gunmisfires quite often, he may strengthen the hammerspring by wrapping rubber bands around theframe and the back of the hammer. This serves toadd more snap to the hammer fall. When such amodification is made, the double action triggerpull is eliminated by removing the entire triggerand sear. The shooter then cocks the hammer backwith his thumb and releases it when he wishes tofire. Most cap pistols can be cocked back fartherwith the thumb than by pulling the trigger. Thus alonger hammer fall is achieved, and this increasesthe momentum and striking energy imparted tothe firing pin. If a gun that is modified in this wayis dry fired the firing pin could snap off due to thebrittleness of the cast alloy, or the hammer couldsnap off at the thinnest part of the shaft. Theheavy blows of the pin against the weak metal ofthe tube barrel may damage the mouth of thechamber to such an extent that no test cartridges

can then be chambered. If the weapon must betested, only .22 B.B. Caps should be used to seewhether the weapon is capable of discharging abulleted load. Anything that has a heavier bulletor powder charge may destroy the casting andinjure the investigator. If it is only necessary totest the serviceability of the weapon, that is,whether or not it will fire a live cartridge, eitheruse a blank load or pull the bullet from a bulletedload and test with the primer only. If soft copper-blanks or B.B. Caps are used to test for service-ability, they may not give a valid test of whetherthe same gun will fire harder brass cartridges. Ifbrass cartridges are found in the possession of anaccused, this hardness factor could be important.

The typical cap pistol that is altered in thismanner has no extractor or ejector yet the shelloften does eject by straight blowback against thehammer. However, the construction of the gunmay be such that the hammer cannot make a fullenough rotation to clear the shell in its rearwardmovement. If the hammer is subject to batteringvery often, it is liable to snap off at its weakestpoint. The piece that breaks could jam into theslot in the frame, but more likely it will be left atthe scene of the crime and will match the shaftleft in the weapon. The break often will not occurwith "standard" velocity .22 short cartridges orwhen .22 B.B. Caps or C.B. Caps are used as thepressure is too low. As with the first weapons dis-cussed in this article, the converted cap pistol hasan i-fitting bore and much of the gas is lost. Ifthe hammer fall is particularly light the triggermay have to be pulled several times or the hammermay have to be cocked and dropped more thanonce. The rim will show multiple strike impressionsplaced close together or overlapping, especially ifthe bore is loose and the cartridge is free to rotatein the chamber with each blow.

BRUCE BARAK KOFFLER

Papetr ca~p

FiGuRE 13A "Shootin' Shell" type of cartridge seen from the

outside and in cross section. A small diameter lead shotmay be used in place of the needle.

MEE SHOOnN' SHELL

Variations of the cap pistol sometimes encoun-tered are the Mattel "Shootin' Shell" guns andreplica toy derringer pistols. These utilize an imita-tion cartridge consisting of a semi-rimmed brasscase having no provision for a primer, and a graycast light metal bullet which appears to be a semi-wadcutter design (fig. 13). The "bullet" runs thelength of the inside of the shell and projects aboutY4 of an inch beyond its mouth. The inside hollow(the "bore") is about Y inch in diameter, but itmay vary. It is not meant to be loaded withpowder. A round cap made o" red paper with adisc of fulminate compound in the center, is avail-able from toy and drug stores. The cap is placedin the bottom of the shell and the bullet is thenpushed in. The bullet does not fit tightly into theshell unless salt deposits from many fired capscause friction between the two pieces of metal.When the cartridge is chambered, the nose of thebullet rests against the rivet that fastens bothhalves of the barrel together. The rear end of thebullet serves as the anvil for the cap. The hammerblow forces the inner surface of the brass shell

Rive+RIBarreljj

FiGURE 14A replica derringer toy pistol; the rivet has been

bored through to permit passage of the needle down thebarrel.

against the cap and there is a small explosion. Itis possible to drill out the center of the rivet sothat the bullet is still held in place. A phonographneedle of the old steel and osmium type for 78r.p.m. records is then inserted into the bulletcavity and can be fired out of the gun. Its velocitycan be increased if the fulminate scrapings from afew caps or the powder from several ground upmatch heads are placed in the bullet cavity, waddedtightly and then the needle is inserted flat andfirst. This activity reached fad proportions in thelate 1950s but has tapered off in the last few years.Two police departments showed me examples ofthis and one officer said that a boy had lost an eyeafter being hit by a finishing nail fired from a"Shootin' Shell".

The derringer type of pistol was banned fromsale in many Ontario cities because it was beingaltered as described, and there were a number ofaccidents stemming from the misuse of these guns(fig. 14). The cost was only about one dollar, andthey were readily obtainable. Caps cost only afew cents, and the needles sold for less than a dollara package. The large Mattel revolvers cost fromfour to ten dollars and so were less readily con-verted by children. However, a number of theseguns have been purchased by adults for use inholdups because the detail on these pistols givesthem a very realistic appearance. The writer hasseen one revolver that had a firing pin fitted andsix barrel tubes soldered into the chambers to fire.22 caliber ammunition. It had been used in anunsuccessful bank holdup in a Montreal suburb.

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Needles fired from these guns are not engravedwith any markings by the gun. They may havetraces of chlorate salts (potassium chloride) andmatch head residue so they should be handled care-fully. Fragments of wadding may also adhere anda shooter's unusual preference may implicate him.Record stores in the area should be investigatedfor recent sales to boys and anybody buying largequantities of needles should be suspected. Finish-ing nails and lengths of hanger wire may also befired from a "Shootin' Shell," but these requirebeing cut to proper length. A tool mark analystcan usually match the cut surface to the piece fromwhich it was cut and to the wire cutters that wereused to cut the metal to size. Such tools as have ametal cutting device should be seized where pos-sible, and an analysis done on them.

BLANK-FIRING REVOLVERS

Blank guns, like cap pistols, offer a completeframe and action and are often much stronger thananything homemade. The writer once saw a R6hmblank revolver with an alloy frame and barreltested for strength. The cylinder was very hardsteel. A number of .22 Ramset blanks with apurple wad (extra heavy load) were fired throughit without damaging the gun. The RemingtonArms Company that manufactures these blanksfor stud driving tools says that even the lightestof their loads may ruin a well-made sporting armin good condition. Some blank gun manufacturersrecognize that their product may be doctored forthe use of bulleted loads and may build in safe-guards. Others such as the manufacturers of verycheap Italian blank revolvers that sell for aboutthree dollars, use the poorest quality castings oflight metal. Close inspection of some models makesone hesitate even to fire blank loads in them. Whenthese are converted to fire bulleted loads, theshooter is asking for trouble.

The cylinder in some blank revolvers is madetoo hard to alter by drilling, and the section of thechamber ahead of the cartridge is factory boredto a narrower diameter than a .22 caliber bullet.At that point it is about .175 caliber. (See fig.15A.) In some models a pin is inserted into thebarrel wall through the bottom and goes part wayinto the top wall. (See fig. 15B.) Because it doesnot go completely through the top of the barrel,the pin cannot be punched out to clear the boreand allow a bullet to pass. The bore is sometimesundersized between the cylinder and the muzzle.The R6hm "RG" series blank revolver has all

FIGURE 15(A) A blank revolver cylinder, with one chamber in

cross-section. The narrower half of the chamber swagesthe .22 calibre bullet, making it longer and thinner. (B)The barrel of one type of blank revolver. The pin can-not be driven out easily as it does not go all the waythrough the barrel. The muzzle is threaded for a signalflare attachment.

of the above features. The writer examined onethat had had the barrel cut off just behind thepoint where the pin passed through it and testfired the weapon. Pressure was extremely high andthe bullet appeared to have been swaged through adie, coming out longer and thinner. The shellexpanded at the rim and the base stretched tofill the hole that the firing pin comes through. Itresembled figure 7 in appearance. It was nearlyimpossible to turn the cylinder by hand for thenext shot, and the second shot effectively lockedthe cylinder fast. Although in most circumstancesthis would prevent the discharge of subsequentshots, the first one before the gun seized up couldcertainly be lethal. The chambers of these re-volvers are usually made to accomodate only a .22Long cartridge; however, some may chamber onlya .22 Short blank and even a .22 Short bulletedround will not fit. When a bullet is swaged throughan undersized bore it will be engraved with de-pressions duplicating the irregularities of thebarrel. No rifling marks will be present as blankrevolvers are not rifled. In some of these weaponsthe front section of the bore is threaded to accepta signal rocket attachment, and these threadsmay account for deep gouges sometimes on bulletsfired through this type of barrel. The bullet maynot be scored by the threads in the same way everytime so one should not *nvest too much faith insuch markings as indentification characteristics.

BRUCE BARAK KOFFLER

A

.22 .22 .22

BL F B.B..AP L=

__F BUM___

FxGuRE 16(A) Magazine for Czechoslovakian blank pistol. (B) Muzzle arrangement on unaltered pistol. (C) Revolving

cylinder. The firing pin is eccentric, on the left face. (D) Altered muzzle, and magazine, with .22 Long Rifle car-tridges loaded. (E) Burst shells. Extraction is difficult. (F) Three types of cartridges that may be used in this pistol.Note the difference in length and the effect that this would have in a short magazine of the kind supplied.

If an attempt is made to rebore the barrel or thecylinder, the same situation may result as isdepicted in figure 4 and the bullet will be shaved.Shaving also is usually present in rebored revolversthat are made with a solid barrel and a top gasport.

OTHER PROBLEMS

As these revolvers are not intended for bulletedloads, no real effort is made by the manufacturerto ensure proper indexing or locking. The timingmay be faulty to begin with or may rapidlydeteriorate if too many bulleted loads are per-mitted to batter soft metal parts. These variablesmay impart a whole series of shave marks to firedbullets, and the extent of the lead loss can be

expected to differ from one chamber to the next.Therefore, it is important to test fire all chambersin a particular cylinder to match test bullets withcrime bullets. Occasionally, a revolver will beencountered that has had its barrel completelysawed off at the frame. Since most cast frames aremade in one unit with the barrel, the lattergenerally cannot be removed by unscrewing it inthe manner possible with a regular revolver. Sincethe powder of a .22 Long Rifle is high speed loadedfor use in at least a sixteen inch barrel, a sawed-offrevolver produces a spectacular muzzle flash andan unnerving amount of noise. Most of the powderbums outside the barrel and can cause a bad bumat close range. Some of the powder load will becarried into a wound channel or be deposited in a

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FIGURE 17A Gecado blank pistol with fluted bore. The bore is

made for firing small signal flares and tear gas car-tridges. It is similar to the design of the Perfecta bore,but the action is completely different.

circle on clothing when a cartridge is fired closeto a person from a weapon with no barrel. Theblast and the heat it produces causes the baseof the lead bullet to upset violently. This extremedegree of upset will give a good indication to theinvestigator of what kind of weapon to search for.If the barrel has been sawed off sloppily, theprojecting edges of metal at the "muzzle" willscore the flared edges of the bullet's gas cup. If ascrew-in barrel is removed from the odd gun thatis manufactured with a separate one, the base ofthe bullet will be tom by the threads inside theframe of the weapon as it passes over them.

In a discussion of any of the above weapons itshould be remembered that they differ from thecrude zip gun both in general reliability' and inthe provision for firing several shots in rapidsuccession. However, these features tend to de-crease in importance with the amount of abuseapplied to the weapon and with the number ofhigh pressure cartridges fired from it.

A BLANK-FrRING "AuTomA c REvOLvER"

There is a blank pistol manufactured to looklike an automatic pistol but which functions like arevolver. This weapon is Czechoslovakian anduses a small square magazine holding four .22 Shortcrimped blanks pointing forward (Fig. 16). Themagazine slides into the gun from the right side,and the four gas holes point forward through onelarge opening in the frame of the pistol. Thefiring pin is an off-centered projection on thecircular face of a small cylinder as shown in fig.

16C. The cylinder has four evenly spaced ratchetteeth on its circumference. Pressure on the triggercocks the cylinder on the shaft that passes throughit, and a ratchet hand simultaneously rotates itone quarter turn. At the end of its rearward cycle,the cylinder is tripped .and flies forward underspring pressure to fire one round. To convertthis weapon to fire bulleted loads, the muzzlemust first be cut and filed to permit entry ofprojecting cartridges. Caliber .22 B.B. Capsfunction best in this conversion because the longercartridge cases are mostly unsupported and burst.They are then very difficult to remove. When B.B.Caps are used the shell is completely surroundedby steel, and only the bullet protrudes from themagazine.

THE PERFECTA PISTOL

The Perfecta pistol is an unorthodox Germanmodel. It fires .22 Short crimped blanks from atubular magazine that fits into the butt; theblanks are inserted into the tube from the top,rim downward. This gun differs from most in thatit has an extractor (a flat ring) through which theshell fits as it is being chambered. After firing,the trigger is released with a snap, the extractorcams the shell back and down out of the chamber,and the empty casing is pushed out of the top ofthe gun through an ejection port; it rolls 5ver theside and drops near the feet of the shooter. Thereis usually a slight bulge near the rim where theextractor fits around the blank. If this pistol isoperated with B13.s or any other projectiles, theblank expands and locks into the extractor,causing the action to seize up. The gun must thenbe completely dismantled to remove the shell. Itis unlikely that this pistol would be converted,since the instructions provided warn that a jamwill occur if anything other than a blank is used.Although standard models of this pistol have atop gas port, one version has a flare/tear gas barrelthat is deeply fluted. Loosely fitting projectilescan be discharged from this model without causingthe action to seize up. The fluting appears to bedeep straight-cut rifling as the cutaway in fig. 17shows.

OTHER "AuToiATic" PISTOLS

The repeating blank pistols that are mostcommonly encountered are shaped like an auto-matic pistol, are about the size of a small .25automatic firearm, and employ a rectangular

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BRUCE BARAK KOFFLER

! "Gas port,

FiGunx 18A magazine for crimped blanks, showing a chamber

in cross section. Ratchet teeth on the underside pushthe magazine back one chamber for each shot.

moving cartridge magazine that passes over thefiring pin for each shot. Figure 18 illustrates thedesign of the magazine which typically has thecapacity for six blank cartridges. The weaponcannot be fired without the magazine for it isalso the chamber for each blank. With consecutivepulls on the trigger each blank lines up with thefiring pin below and the gas port above. A handengages ratchet teeth on the base of the magazineand moves the metal block from front to rear.When the magazine reaches the back of the gunan additional pull on the trigger moves it backthrough a hinged trap door. The Rbhm, EM/GE,and Gecado pistols as well as more obscure makesare patterned on this design. Most of thesefirearms have a very sharp firing pin, and it cutsa weak point into the soft copper blanks madefor such guns. A barrel attachment is sometimeshome-made to screw into the gas port on top ofthe gun; the original muzzle of the pistol is thenpointed to the ground to direct the attachmenttoward a target (fig. 19). It will fire small shotpellets or steel B.B. shot. If the bore is too tightthe blank case may burst around the firing pinimpression, and the powder gas may damage theaction. Several of these pistols have an escape holeon the left side of the gun to handle the gas safely,but the opening is level with the thumb of theshooter and not too many burns are needed to gethim to smarten up. A small black bum mark willbe present near the web of the thumb after a blankbursts. Although the weapon holds six blankcartridges only one projectile can be fired at atime. The shot pellet must be replaced for each shotand wadded in place to keep it from rolling out ofthe barrel when the gun is tilted. One smart young-ster simply placed a piece of masking tape over the

FIG=n 19A Gecado blank pistol with top gas port and home-

made barrel attachment threaded into place.

Rivet -, p 1"'

ACralre tZII

FioGuR 20(A) Barrel of an "H.S." starter's pistol in cross-

section. If the barrel is drilled through it will fall out, asthe rivet does not have enough metal left to hold thebarrel tightly in the frame. The hole underneath willbleed off gas onto the shooter's trigger finger if thebarrel is bored through. (B) A .22 short crimped blank.The shell is made of soft copper. Actually, the openedshell is the length of a .22 B.B. cap shell, not that of a.22 Short case. These blanks are made only in Europe.

muzzle of the gun to avoid having to wad in eachshot pellet. If a ramrod and soft lead shot are used,identifiable impressions may remain. Usually noworthwhile striae are engraved by the barrel onthe projectile.

THE '"H.S." SINGLE SHOT PISTOL

This starting pistol is the cheapest one madeand possibly the most difficult one to convert. Itsells for two dollars, and is made from three sheetmetal stampings held together with pins and spotwelds. It is a German firearm, and only .22 Shortcrimped German blanks will function because thechamber is so shallow. The cartridge mouth pro-jects downward and the barrel has a hare boredpartway through the bottom wall in line with thecartridge mouth to discourage those who wouldattempt to ream it out to accomodate a bulletedload (fig. 20). The gas port is on top of thebarrel which is riveted through the center to the

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FIGURE 21A homemade semi-automatic Zip Gun. The hammer

recocks and stays locked back, even if the finger is onthe trigger.

sheet metal frame. The hammer is designed forsoft copper blanks and often the wide firing pin willnot detonate the primer in a hard brass shell on thefirst blow. Although this pistol is inexpensive, itmust be reworked at more expense than would berequired to build a gun using the same design frombasic materials. The barrel must be removed bypunching out the soft metal pin and then it has tobe cut and bored. The firing pin shape needs to bechanged, and a stronger hammer spring must besubstituted for the original one. Space limitationswithin the frame make this a difficult proposition.Several boys in a high school machine shop copiedthe design and for about fifty cents were able toturn out a product that they were selling for fivedollars. Figure 21 illustrates the design- that isbasically that of its German counterpart. It is twoby two and one-half inches square including thebarrel. All parts are heavy sheet metal spot weldedtogether. The barrel is made from bar stock boredon a drill press, and the two small springs werepurchased at ten cents apiece. The frame is onlythree eighths of an inch thick. This weapon fires.22 Short and B.B. Cap ammunition, ejects emptyshells and recocks automatically, just like theoriginal. Its accuracy from the one inch barrel istwo feet for practical purposes, since the entireweapon is put far out of line of sight with a tinymotion of the wrist. There is so little to hold onto,that it is difficult to point it at waist level withoutlooking at the gun at the same time to be sure it ison target.

FIGURE 22A blank revolver of the type made by Iver Johnson

and by Harrington and Richardson. The pointed ex-tension may be cut off and the barrel bored through.The bullet has to jump an inch from the cylinder to thebarrel and would be "shaved" and badly deformed.

AmERICAN-MADE BLANK RE-voLvERs

Iver Johnson and Harrington & Richardsonboth make a rather expensive blank revolversimilar to figure 22. There is no barrel used as such.An extension of an imitation solid barrel has apoint that sits directly in front of the uppermostchamber. This point deflects gas to the sides andhelps to break up any wadding that is still poten-tially dangerous to bystanders. Since it is so expen-sive in comparison to imported models, few storessell them except as a special order item. It isunlikely to be found in juvenile hands althoughremoval of the "barrel" could easily convert thispistol into a deadly weapon. The writer knows ofno instances where such a pistol has been convertedto fire bulleted loads.

TEAR GAS PENS

Most tear gas pens sold today do not use acartridge that fits into a barrel because the earlierprojectors were too easily converted. Recentmodels have no barrel but use a type of cartridgethat screws into the front end of the device. If thethreads inside the projector can be duplicated, ascrew-in barrel can be made. Since most of theprojectors on today's market are center fire .38caliber models, a .22 barrel must be bored off-center to allow the firing pin to strike the cartridgerim. These guns are often unsafe to use in theunaltered condition because there is no positivesafety device to prevent accidental discharge. Twomodels have a safety notch for the cocking handle,but tests show that this is not to be trusted, espe-

BRUCE BARAK KOFFLER

cially with a bulleted load in place. One Japanesegas pen has a barrel that unscrews to accept a .38tear gas cartridge. This cartridge is the standard.38 Special case carried by police officers but loadedby two companies with gas-producing powderinstead of a bullet. The manufacturer warns thata ball cartridge will destroy the device and injurethe shooter. It is possible to put an off-center .22bore liner into the manufactured barrel and fire itas a single shot weapon. This device has the appealof a weapon disguised as a pen, and is easily carriedin the shirt pocket without arousing suspicion.Fired bullets are engraved with the irregularities ofthe barrel and can be analysed for individualcharacteristics. One device that was actually madeto look like a pen but fired .22 bulleted loads wasmanufactured by R. F. Sedgely, Inc., in Phila-delphia. It looked exactly like a fountain pen andhad a short rifled barrel. Very few of these are incirculation at present, because none have beenmade for 35 years.

Police gas billy sticks take a 12 guage shotgunshell that is loaded with a lacrymatory powder.The writer has seen one of these fired with a shot-shell intended for hunting use. The nightstickcracked with the first round, and a subsequent shotwould have burst the chamber. Loosely mountedin a vise for testing, the nightstick jumped fromits grip and flew across the room. The recoil wouldlikely be enough to break a wrist if the device wereto be fired with one hand.

FLAniE PisroLs

These military signal pistols are available in20mm, 25mm, and 37mm types. The first size wasused niostly by Germany in the last two wars.Britain has favored the 25mm caliber; while theUnited States has used it along with the 37mmsize. The British models follow the Webley designwhile U.S. models in common circulation are madeby Harrington & Richardson. Most types areproofed for a black powder launching load, and theBritish models bear the '".P." proof mark toindicate this. American firearms do not require aproof mark. A flare cartridge may be reloaded witha shot charge, but the primer may be difficult toobtain as it is an odd size. An insert tube may bemade to fit the pistol's bore and chamber a 12gauge shotgun shell. It is difficult to find pipe witha large enough outside diameter to fill the bore andwalls thick enough to accept the much smallershotshell. Of course, the smaller the gauge theharder it will be to solve the problem. An insert

may be machined to proper fit, inside and out andthen soldered in place. More common is a systemof telescoping tubes that have been crudely filedto fit tightly within one another. The innermosttube that serves as the bore is difficult to fileaccurately. If it is too loose the shell will burst.If it is very tight the shell cannot be extractedeasily and irregular areas of the bore will leavehighly individual characteristics on the brass por-tion of the shell. The pistol must be fired with theleft hand around the barrel to absorb the heavyrecoil. Commercial inserts for several of these pis-tols were made during the last war and some weremade on special order for police departments.These were made only in twelve gauge and hadprovision for the pistol's extractor to remove theempty shell. The writer has seen no homemadeinserts that allow for extraction and pistols con-verted in this way are clumsy to use for more thanone shot.

PELLET-UIING WEAPONS

Air guns offer considerable scope for illegalconversions. To cock the gun a spring loaded pistonis pushed to the rear and locked in place by thesear. The trigger releases the piston and air com-pressed ahead of it thrusts a pellet, B.B., or dartdown the bore. To convert a pellet weapon to firelive ammunition, a precondition is that the pistonbe in direct line with the bore. The Webley pistolhas the piston beneath the barrel and is cockedfrom back to front. It cannot be altered in themanner described here. To convert the Falke,Diana, Marksman, and other pistols, the face ofthe piston must be fitted with a firing pin thatprojects out to the edge of the chamber mouth.A hole may then have to be drilled to relieve airpressure as the piston moves, or the piston can besanded down to remove the hermetic seal. If airpressure is unrelieved, the firing pin will move tooslowly to positively fire the primer. The bore in a.177 pellet gun and a .175 B.B. gun is unsuited forcartridges because it is too narrow. If the chamberis reamed out a .22 B.B. Cap can be shot withreasonable safety. The bullet is swaged by the borein a way similar to figure 16 A. If a longer and morepowerful .22 load is to be used, the entire barrelmust be rebored. In a long barrel, the boring isoften done from both ends since a drill bit therequired length is seldom available. The planingeffect this often produces on the bullet, as wasdescribed in an earlier section, can be expected tobe present. The only way around the problem of

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FIGuRE 23A .22 B.B. cap shell fired by slamming pellet rifle

barrel shut.

barrel length is to shorten the barrel before boringit. When this is done, rough edges left around themuzzle can provide some identifiable characteris-tics. In altering a gun originally chambered for a.22 caliber pellet, the shooter need only lengthenthe chamber. Rifling in these weapons is usually amicrogroove type with as many as 14 grooves.This can be troublesome to identify on .22 bulletsswaged down to .177 inches, but with patience apositive match can be made.

Most of these weapons are designed as singleshot break-action guns. A .22 B.B. Cap can befired from some .22 pellet rifles without makingany change in the action. The cartridge is insertedinto the chamber and the barrel is slammed dosed.Since there is not enough clearance for the rim itis crushed by the sudden force put upon it. Theround fires and internal gas pressure against thebase of the cartridge bulges it back into the airholebetween the piston cylinder and the barrel. Theeffects of this are illustrated in figure 23. The basemetal appears to have been "smeared", and thisis complicated further when the barrel is brokento reload. The' bulged area of the shell is scrapedagain by the top edge of the airhole. The cartridgecase is longer than the pellet meant to be used inthese guns, and it extends into the rifled portionof the barrel. Gas pressure forces the case into thegrooves and an impression of the rifling is left onthe outside. These striae are not as useful foranalysis as those engraved on a bullet that hastravelled the length of the bore. If nothing else,

they can provide a count of the number of the landsand grooves in the particular rifle if the recoveredbullet is badly deformed.

HEvv CALiBER Zip GuNs

Most youngsters have no comprehension of theenergy stored in a high-power rifle cartridge or aheavy-gauge shotshell. They construct guns to firethese and are often maimed by the resulting explo-sion. The 12 gauge shell is the usual one encoun-tered, because it easily fits old plumbing pipes,television antenna masts, and tubular chair legs.If a threaded plumbing pipe is used for a barrel acap may be affixed to the breech. A cap pistolaction or a rubber band and a nail is then mountedto set off the primer. The shooter is then holdinga bomb. Alert citizens often report this type ofweapon to the police who then confiscate it beforeany damage is done. Many potential victims havebeen spared in this way. The investigator shouldnot be so bold as to fire it by hand. If it must betested, the weapon should be set up with sandbags shielding it on all sides. The investigatorshould then fire the cartridge remotely by a longstring. It is not necessary to use a full charge, andif the gun must be saved intact as trial evidence,firing a primer should be enough to prove theserviceability of the action. It might be worthwhileto blow up a gun, collect, and mount the fragmentsand display the remains of the weapon in schools,at the same time the local police are carrying outtheir annual "Report Blasting Caps to YourTeacher" campaign.

LETHAL EFEcTs

The .22 Long Rifle high speed cartridge is theone most often fired in zip guns. The workingpressure developed depends on the amount ofpowder that is burned. This varies with the indi-vidual gun as some have very tight bores if drilledout with a Y3 2 inch drill bit while others made from.25 inch car radio antenna tubing are so loose thatthey barely hold the rim. A loose one usuallycauses the case to split and most of the drivingpressure is wasted. If a suspected crime weapon istested with the type of cartridges that were usedin the crime, and the bullets fairly roll out of thebarrel, this is unlikely to be the one used in a fatalshooting. A confirming factor is a deformed bulletthat has penetrated deep into flesh, and a recoveredcartridge case showing signs of high pressure (aflattened rim, for instance). The identifying charac-teristics of the crime gun should be reproducible

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BRUCE BARAK KOFFLER

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FIGURE 24A Hollow-point bullet fired from a revolver without

a barrel. The base upset from hot, high pressure gasrushing out around it as the bullet emerged from thetight cylinder into the wide bore left by removal of thebarrel. The hollow point expanded when it penetratedflesh.

in the laboratory to the same extent with a zip gunas for any commercial firearm. In an earlier sectionit was stated that the base of a lead bullet willexpand if it is fired from a revolver without abarrel. A .22 bullet may nearly double in diameterat the base. If it is a hollow point bullet and strikesan object or a body point first, it will expand infront as well as around the gas cup. Thi: barbell-shaped slug tumbles as it makes a wound channeland is capable of inflicting great tissue destruction.Figure 24 shows a bullet that has been distorted atboth ends. The large base will cause an entrancehole, in tissue, that is bigger than what a .22 bulletwould normally produce.

No definitive statement about every possibletype of projectile used in a zip gun can be made.There are too many variables involved becausenearly anything that can be inserted into the boreof one of the muzzle-loading weapons is a potentialbullet. Marbles, carpet tacks, ball bearings, phononeedles, pieces of hanger wire and of course regularbullets have all been fired from homemade weap-ons. One police museum had a box of .30 caliberrifle bullets that had been pulled from rifle car-tridges with pliers. An exploding bullet for a fire-cracker zip gun had been made by drilling out thecenters of these soft point bullets from the frontend, and inserting a Remington "Rocket" highspeed .22 Short cartridge bullet-first into the noseof the .30 caliber projectile. The rim of the .22shell protruded and the projectile exploded whenfired at any surface that provided the slightestresistance. The live cartridges fired from anothergun were described earlier. The effects in tissue are

beyond the experience of this writer, but it can bepresumed that the shock effect of an explodingbullet would be far more devastating than anexpanding bullet produces. Kitchener, Ontario,police tested a marble-firing firecracker zip gunsome years ago and found that it would go througha steel 45 gallon drum. The marble emerged nearlyintact. Police in Whitby, Ontario, tried a similarweapon about the same time and fired a marblethrough a 2 inch plank. B.B.s or small shot can belethal if used in large quantities. A mass of themdriven by a cannon firecracker can be as effectiveas the shot charge from a .410 shotshell. Carpettacks and other sharp objects can produce terriblelacerations. The writer tried these on the carcass ofa groundhog and found the skin to have manyjagged splits. All irregularly shaped projectiles willtumble to some extent if there is no rifling tostabilize them and keep the point forward. A shortdistance from the muzzle yaw begins and themissile strikes broadside. All of one side of a leadbullet which has struck in this way often bears theweave pattern of the victim's clothing. This provesthat the bullet actually did not strike point first.

A particular weapon or load may be moredamaging to the shooter than to his intendedvictim. Large caliber cartridges in an inappropriateweapon can produce the effects of an offensivegrenade as pieces of metal fly in all directions (ref.1). Burst .22 shells may cause facial lacerations tothe shooter and to bystanders. Blank revolversthat do not index correctly shave lead off the bulletas it passes from the cylinder to the barrel. Thewriter had fragments of lead embedded in hisindex finger at bone level for many years after testfiring a weapon of this type, without wearing heavygloves for protection. The eyes of a shooter arealways endangered by flying shells, shell fragments,and searing gas. His hand shows powder burns ifthe weapon is not gas-tight. Finally, a convertedsignal flare pistol is a sawed-off shotgun both inclassification and in degree of effectiveness. Theappearance of a 1% inch diameter muzzle usuallyconvinces a potential victim that it might be betternot to be shot. The bank robber who uses one ofthese weapons understands the psychological effect.

CONCLUSION

The writer has presented a broad descriptiveoutline of many types of zip guns. Some varietiessuch as the one described in the November 1966F.B.I. Law Enforcement Bulletin are not true gunsin the sense of the word used in this article. If it is

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ZIP GUNS AND CRUDE CONVERSIONS

not a powder-operated firearm, it is a projectorrather than a gun. In the past, the literature onfirearms and criminology has largely ignored thespecial problems of these weapons. That thesefirearms do in fact pose a threat in some urbancenters was pointed out by a member of the NewYork City Police Ballistics Squad as this articlewas in preparation. He related that in an averageweek about 35 or 40 homemade weapons are seizedby his department. Many more go undetected.In a city that has probably the most restrictivepistol laws on the continent, we have an exampleof how such legislation fails to achieve its purpose.The individual who cannot legally obtain a firearmand wants one badly enough can make a service-able weapon in very short order and with limitedskills and tools does a reasonable job. The samedetective made it clear that this was not just ajuvenile problem. Adults with a little more pocketmoney, access to better materials, and having theuse of more machine tools can turn out a betterfinished product that is usually quite safe andaccurate. Fifty percent of the zip guns in NewYork City are made by adults. When we ask forstricter gun ownership legislation in future, this issomething to bear in mind.

ACKNOWLEDGEMENTS

The writer wishes to acknowledge the help andassistance of the following in the preparation of

this article: B. Bryks, Mrs. D. Koffier, ProfessorsR. Vastokas and K. Kidd, both of Trent Univer-sity, J. Wolff of Albion Arms, Inspector J. Conlinof the Peterborough Police Dept., Sgt. M. Inglisof the Toronto Police Dept., Special Agent L.Smith of the Florida Sheriff's Bureau, V. Krcmaat the Quebec Institut de M~icine L~gale, andDet. R. Clancy of the New York City PoliceBallistics Squad. Many other police agencies anddepartments also contributed significant informa-tion.

REFERENCES

1. Toy Guns, R.C.M.P. QuAIRERuY, Vol. 32, Number2, page 21, 1966.

2. ROBERT R. LENZ, ExPLosivs AN BomB DISPOSALGUmE, Charles C Thomas, Springfield, I].: 1965,page 58.

3. GERMAN INFANTRY WEAPONS, Normount Arma-ment, Forest Grove, Oregon: 1966.

4. A. SvENssoN AND 0. WENDELL, Revised by J. D.NlCOL, TECHNIQUES oF C SCENE INVESTIGA-TIn, (2nd American edition) Elsevier PublishingCo., New York: 1965.

5. H. J. FUNK, Comparison of Paper Matches, JouRNALOF FORENSIC SCIENCES, Vol. 13, Number 1, Janu-ary, 1968.

6. Investigator's Aids-Firecracker Weapon, F.B.I.LAw ENFORCEMENT BULLETiN, March, 1968, page11.

7. Zip-Gun, F.B.I. LAW ENFORCEMENT BULLETIN,Nov., 1966, page 19.

8. LESLIE L. SMIT, Unusual Handguns, JouNAL oFFORENSIC SCIENCES, Vol. 6, Number 4.

9. LESLIE L. SMEIM, Zip Guns, PoLICE, January-Feb-ruary, 1963.

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