Gunsmithing Terminology Flashcards
Learn the definition of different terminology as a gunsmith. (163 cards)
1
Q
ACP
A
Stands for “Automatic Colt Pistol”. Used
to designate certain cartridges first chambered (in
the USA) in Colt automatic pistols – .25 ACP, .32
ACP, .380 ACP, .38 ACP, .45 ACP.
2
Q
ACCURIZE
A
Improving the accuracy of a
handgun, usually an auto pistol, by reducing
tolerances between parts.
3
Q
ACTION
A
Action of a rifle is the actual firing
mechanism or the complete mechanism of the
firearm exclusive of the barrel and stock. It is the
means by which the gun is loaded, and which
secures the cartridge in the chamber against
discharge to the rear.
4
Q
ACTION, BOLT
A
A breech action of a rifle
which is opened, closed and operated by means
of a bolt, the latter having a handle.
5
Q
ACTION, LEVER
A
A breech action which is
opened, closed and operated by means of a lever
formed as a rearward extension of the trigger
guard.
6
Q
ACTION, PUMP
A
A breech action which is
opened, closed, and operated by means of a sliding fore-end which is formed into a convenient
handle for this purpose. Also termed slide
action, falling block, swinging block, rolling
block, break, gas (semi & auto) recoil, semi-auto
straight blow-back (semi & auto), delayed blowback (semi & auto).
7
Q
AMMUNITION
A
Cartridges, shotgun shells or
both.
8
Q
AMMUNITION, METALLIC
A
Cartridges
loaded in metallic shells or cases. Used in the
trade as referring to rifle and pistol cartridges to
distinguish them from shotgun shells, which are
usually loaded in cases made principally of paper
or plastic.
9
Q
ANVIL, PRIMER
A
A small pointed piece of
metal inserted in a primer on which to crush
the priming composition thus causing the spark
which ignites the powder. See PRIMER.
10
Q
ANNEAL
A
To anneal steel or other metals is
to render it soft. It is usually accomplished by
heating it to a red color and allowing it to cool
gradually.
11
Q
ASSAULT PISTOL
A
A high-capacity, full
automatic firearm styled like a sub-machine
gun, but having a pistol-length barrel and
lacking a fixed buttstock, such as a PDW
-personal defensive weapon- (i.e. Cooray MI1/
CZVZ61 Skorpian).
12
Q
AUTOMATIC
A
A term commonly used for a
self-loading firearm. A firearm is truly automatic only when it continues to fire as long as
the trigger is held back. Full automatic firearm
possession without proper documentation is
illegal in this country.
13
Q
BALANCE
A
The balance is literally that point between butt and muzzle where a gun balances when rested on a fulcrum. However, this
is not the popular understanding of the term.
Neither is it an entirely popular understanding
that a gun balances properly when the point of
balance is midway between the points where
the hands naturally hold it in shooting. In most
cases, balance is understood to mean the feel it
gives to the shooter in handling the gun that is,
whether correctly balanced or either muzzle
light or muzzle heavy.
14
Q
BALLISTICS
A
The theory of the motion of
projectiles. The American shooter loosely
considers “ballistics” to mean the data relative
to the velocity, energy, trajectory, and penetration of a cartridge.
15
Q
BALLISTICS, EXTERIOR
A
The theory of
the motion of the projectile from the gun to the
target.
16
Q
BALLISTICS, INTERIOR
A
The theory of the
motion of the projectile in the firearm.
17
Q
BALL POWDER
A
-see OLIN BALL POWDER.
18
Q
BARREL
A
Steel tube of a firearm through which
the projectile is driven. It directs the projectile
toward its target.
19
Q
BARREL LENGTH
A
Per Federal Firearms Act of 1935 and the most recent
amendment which became effective on July
1, 1960, no rifle can have a barrel length less
than 16 inches or a shotgun have a barrel length
less than 18 inches in length overall. Any rifle
or shotgun that can be converted to an overall
length less than 26 inches is illegal
20
Q
BASE WAD
A
A compressed paper filler inside
the head of a shot shell, used to keep the powder in position in front of the flashing end of
the primer. Latest loadings of Super-Speed and
Super-X 12-16-20 gauge shells do not have base
wads. Both have the new, ultra strong, all plastic,
compression-formed cases.
21
Q
BEAVERTAIL
A
A fore-end grip of a shotgun or
a target rifle which is made wider than a standard
fore-end. From the shape of the tail of a beaverwide and flat.
22
Q
BENCH REST
A
A bench table, arranged so as
to provide mechanical rests for the forearm or
barrel of a rifle and a marksman’s elbows, the
marksman being seated at the table. Used for
accurate firing in testing a rifle or ammunition,or
both.
23
Q
BEVEL BASE
A
Any bullet design in which
there is a slight bevel between the base and the
bearing surface proper.
24
Q
BIG BORE
A
See “large bore.”
25
BLOWBACK
An operation system in
self-loading firearms in which the slide or
breechblock is driven to the rear by direct gas
pressure on the cartridge case head.
26
BORE
The hole through the barrel of a firearm.
In a rifle the bore is the hole after it has been
drilled and reamed, and before rifling; that
is, the bore diameter of a rifle is the diameter
measuring to the top of opposite lands. Bores are
usually measured in fractions of an inch and in
millimeters. The groove diameter is the diameter
to the bottom of opposite grooves. See CHOKE
(with regard to shotguns).
27
BREECH
The rear end of the bore of a firearm
| where the cartridge is inserted into the chamber.
28
BREECH BLOCK
The steel block which
closes the breech of a firearm, sustaining the
head of the cartridge when the gun is fired.
29
BREECH BOLT
Part of the action which
closes the breech. The part which locks the
cartridge in place. The word "Bolt" is commonly
applied to this part in bolt-action, lever, pump
rifles and semi-automatic rifles. In some instances
such as falling-block, single-shot actions, the
corresponding part is called a breech-block.
30
BREECH PRESSURE
The peak of the rearward pressure exerted by the detonated powder gas
in the bore of a firearm when a given cartridge is
fired therein. It is expressed in pounds per square
inch, and is measured with a pressure gauge.
31
BULLET
The projectile for a firearm.
Projectiles are made in many shapes, sizes and of
many different materials. The most common type
of bullet is the regular, solid cast bullet made from
lead or some alloy of lead. A regular-jacketed bullet consists of a jacket made of copper or an alloy
of copper or steel with a lead core. Jacketed bullets are made in several types such as hollowpoint,
softpoint, or full metal jacket. Soft and hollow
pointed bullets were sometimes called dum-dums.
The term "dum-dum" applies more or less to bullets that will upset or expand upon impact. Some
jacketed bullets are made with bronze or steel points and special types of bullets are made which
are called armor-piercing or incendiary.
32
BULL GUN
A target rifle with extra heavy barrel.
33
BUTT
Part of the gun stock which comes in
| contact with the shoulder of the shooter.
34
BUTT PLATE
Plate used to cover the end or
butt of the stock. It is made from various types
of material such as metal, horn, plastic or rubber.
When made of soft rubber it is termed a recoil
pad.
35
CALIBER
Actual diameter of the bore of a
rifle. It is commonly measured in two ways:1. By
actual bore diameter; 2. By the groove diameter. In
America and England it is expressed in decimals
of an inch, and in Europe it is expressed in millimeters.
36
CAM
In guns, usually takes the form of a
slanting surface which, when rotated, will move
a contacted part backward or forward. Cams are
commonly used in firearm actions to accomplish
the actual locking operation or to accomplish
other functions such as cocking.
37
CANNELURE
A depression or groove rolled
into a bullet or cartridge case. Cannelure in a
bullet can be plain or knurled and it sometimes
functions to crimp the cartridge down to retain the
bullet in place. Another function is to help hold
the lead core within the jacket. A cannelure on
a case is simply a groove rolled in the neck at
the proper point to keep the bullet from sliding
too far into the case. Entirely lead bullets have
numerous cannelures for the retention of grease
or lubricant.
38
CANT
Leaning of a rifle to one side or the other
so that the sights are not in a truly vertical plane.
Canting a rifle to one side causes its bullet to
strike the target on the opposite side of the cant
and slightly high.
39
CAP
Metal covering for a pistol grip or the end
of a forearm. It is also used in connection with
percussion caps used for detonating muzzleloading firearms of the percussion-cap type. Such caps are usually referred to as percussion caps instead of caps.
40
CARBURIZING
(carbonizing) Heat treatment
of low carbon steel to introduce carbon into
the surface which produces a hard skin when
quenched.
41
CARBINE
A short-barrel rifle commonly used
by troops on horseback. Still in military use in
varied applications.
42
CARRIER
The mechanism in a magazine or
repeating firearm (not a revolver) which carries
the shell or cartridge from a tubular magazine
into a position to be pushed into the chamber by
the closing of the breech bolt.
43
CARTRIDGE
The fixed ammunition of
metallic type for a firearm. A cartridge is an
assembly of (1) case, (2) primer, (3) powder
charge, (4) bullet or projectile. Therefore, the
word cartridge applies to the four component
parts assembled into one element.
44
CAST-OFF
Distance a stock is offset to the
right from the line of sight or from the axis of
the bore, away from the face of a right-handed
shooter. Many double guns are slightly cast off
but few are cast on.
45
CAST-ON
Term used when the stock offset is
to the left. Cast-off is commonly used for the
right-handed shooter; cast-on for the left-handed
one.
46
CENTER-FIRE
Term applies to a firearm
which uses a cartridge with the primer in the
center of the case head.
47
CENTER FIRE CARTRIDGE
A cartridge having the primer containing the priming composition inserted in the center of the head of the
shell or case.
48
CENTER PUNCH
Punch with a short sharp point for making marks on metal. The 600 "center punch" is used to enlarge marks made with the 300 "prick punch" when precision layout is required.
49
CHAMBER
Enlarged recess in the breech of a
firearm which is provided to accept the cartridge
or shell.
50
CHASERS
Special tools for cutting threads.
51
CHECKERING
Applies to diamond-shaped
patterns cut in wood or metal parts for the
purposes of minimizing slippage, and for the
purpose of ornamentation.
52
CHEEK PAD
A leather attachment with rubber
padding inside which is provided to raise the
comb of a shotgun or rifle which the shooter
finds too low to fit him satisfactorily
53
CHOKE
The constriction in the muzzle end of a
shotgun bore by means of which control is exerted
upon the shot charge in order to throw its pellets
into a definite area of predetermined concentration.
Degree of choke is measured by the approximate
percentage of pellets in a shot charge which hit
within a 30 inch circle at 40 yards. The following table gives the accepted percentages obtained
with various chokes:
Full Choke . . . . ... . ... ......65-75%
Improved Modified . . . .. . 55-65%
Modified ... .. .. . .. .. . .......45-55%
Improved Cylinder .. . .......35-45%
Cylinder Bore . . ... . .. . . ...25-35%
54
SKEET PATTERNS
Winchester Skeet Choke
gives a 95% pattern in a 38" circle at 20 yds. and
a 95% pattern in a 48" circle at 25 yds.
55
CHRONOGRAPH
The instrument used to
| determine the velocity of a projectile in flight.
56
CLIP
A device for holding cartridges
together, usually to facilitate loading. Erroneously used as a synonym for "magazine". A magazine has a feeding spring, a clip does not.
57
COCK
To pull the hammer or firing pin of a
gun back to full-cock so that the firearm is ready
to fire. A firearm with a visible hammer usually
has half-cock and full-cock positions.
58
COCKED AND LOCKED
The practice of
carrying a self-loading pistol with a round in
the chamber, the hammer cocked and the safety
engaged.
59
COCKING PIECE
Piece attached to the
projecting end of the firing-pin in bolt-action
rifles. Cocking pieces are normally made in two
styles, head and headless. A good example of
the head-type is the 1903 Springfield, which has
a large head or knob on the large end of the
cocking piece which can be grasped with the
thumb and forefinger, thus enabling the shooter
to manually cock his rifle. The headless type
of cocking piece is either plain or has a small
groove or some provision for insertion of a
cartridge rim or screwdriver or some other tool
to allow withdrawal of the cocking piece and
thus cock the firearm in case of misfire, without
the necessity of unlocking the bolt with the
accompanying danger of the misfire being due to
hangfire or delayed-action, which would create a
dangerous situation
60
COMB
Top of the butt stock or part of the stock
which extends from the heel to a point just back
of the hand as the stock is grasped. It is the part
of the stock on which the cheek rests at the time
of firing. A proper comb guides the face to such a
position that the eye falls quickly into the line of
aim.
61
COMB OF STOCK
The upper edge of the butt
stock. The forward, highest point is called the
point of the comb.
62
COMPRESSION-FORMED
A process of
forming an all plastic one-piece shot shell case
from a "slug" of plastic. Does away with paper
base wad and overlay wad. Strongest possible
construction.
63
CONE
The slope of the forward end of the
chamber of a shotgun which decreases the chamber diameter to bore diameter. Also called forcing
cone.
64
CORDITE
Type of powder used by the English to designate smokeless. A nitro-glycerine
base powder, actually a form of dynamite and
extremely hard on the bore of a rifle. It is still a
popular propellant in England, especially for bigbore rifles used in Africa.
65
CRANE
The swinging unit that hinges the
| cylinder of a revolver with the frame.
66
CRIMP
In rifle or revolver cartridges, the slight
bending in of the mouth of the case so that it
grips the bullet, thus securing the bullet in the
case.
67
CROSSBOLT
Transverse bolt used to lock
the standing breech and barrels of a shotgun
together
68
CROSSHAIR
Type of reticule consisting of
fine crossed wires or hairs to designate the center
of the optical field in a telescope sight.
69
CUP WAD
A patented development first introduced by Western, which, coupled with
exclusive base wad (see base wad),
actually "seals in" all powder gases and forms a
sealed gas chamber. Cup wad is just in front of
powder.
70
CUT OFF
Part found in some rifle actions
which can be arranged to temporarily prevent
cartridges from feeding from the magazine into
the chamber when the bolt or mechanism is
operated.
71
CYLINDER
Usually applied to the part of the
revolver which contains the cartridge chambers
and which revolves so that each cartridge lines
up in turn with the barrel. It is used also in
connection with the description of a rifle barrel
and applies to that part of the barrel which
extends just forward of the receiver.
72
DAMASCUS BARRELS
A type of
ornamental metal used in the manufacture of shotgun barrels. Damascus applies to a
combination of metals or different types of the
same metal produced by welding or twisting
together dissimilar strips. Also called "laminated."
Damascus applies to a combination of metals or different types of the same metal produced by
welding or twisting together dissimilar strips.
Withstood pressures of old black powder loads,
but no smokeless powder loads of any kind are
to be used in guns having Damascus or twist
steel barrels. Avoid them.
73
DELAYED BLOWBACK
A variant of the
blowback principle in which the blowback
operation is by some means retarded (e.g. by
fluted or grooved chamber).
74
DIES
A term which can apply to numerous
or several items in reference to guns, the most
important of which are thread-cutting dies;
cartridge-reloading and sizing dies; and dies
for the production of various types of parts
commonly known as stamps, which are found so
often in modern firearms.
75
DISCONNECTOR
A device in auto pistols
that prevents the pistol from being fired until the
breech is completely shut and prevents the pistol
from being fired fully automatic.
76
DOUBLE-ACTION
A type of lock work in
either a revolver or auto pistol which permits the
hammer to be cocked either by direct manual
action or by a long pull on the trigger.
77
DRAM EQUIVALENT
A unit of measure: 16
drams (av.) in one ounce, or 256 in a pound. In
the early days of black powder shot shells, the
powder charge was measured in drams. Drum [or
dram, today's smokeless powder is more powerful. The term "3 dram equivalent" means that the
amount of smokeless powder used produces the
same shot velocity as would 3 drams of black
powder.
78
DRIFT
The deviation of the projectile from the
| plane of departure due to rotation. In all sporting firearms it is so slight as to be of no consequence.
79
DRIFT OUT
Using a punch or similar tool to
| drive out pins.
80
DRIVING BANDS
Portions of a lead bullet's
bearing surface that contact the bore. Driving bands
are separated by crimping and lubricating grooves.
81
DROP
The distance from the line of sight to
the top of the heel or point of comb of the stock
or forearm. Often drop is specified from the line
of sight and also from the axis to the bore, since
the gunmaker is often called upon to build a rifle
complete with stocks, but without sights.
82
DROP AT COMB
The vertical distance between the prolonged line of sight and the point
of the comb. The drop and thickness of the comb
are the most important dimensions in the stock
of a shotgun or rifle. They are affected by and
dependent on the drop at heel. If the dimensions
are correct the eye is guided into and held steadily in the line of aim. The best standard drop at
comb for both rifles and shotguns is 1 1/2 to 1
5/8 inches.
83
DROP AT HEEL
The vertical distance
between the prolonged line of sight and the heel
of the bull. The amount of drop varies, depending upon the ideas and physical
conformity of the shooter. Most shotgun shooters
require a drop of about 2 1/2 inches, usually less
in a gun for trapshooting.
84
EJECTOR
In general, the mechanism which
ejects or throws the empty case or loaded
cartridges free from the gun after it has
been withdrawn, or partly withdrawn, from
the chamber by the extractor. Ejectors are
commonly of two types, selective and automatic.
Specifically, in a break action shotgun, ejector
actually includes the extractor. In double barrels,
selective ejection means automatic ejection of
the fired shell only
85
EJECTOR HAMMERS
In a break action
shotgun the driving pistons which eject the fired
shells, utilizing the extractor(s).
86
ELEVATION
The raise or elevation given to or
required on the rear sight of a rifle to cause the
bullet to strike the target at a given distance.
87
ELEVATION, ANGLE OF
The angle between
the line of sight and the prolongation of the axis
of the bore which it is necessary to apply in
order that the bullet shall strike the target at a
given range.
88
ENERGY
The measure of the work performed by a bullet, expressed in foot pounds.
Energy does not always indicate killing power.
For example, a full-jacketed and soft-point
bullet may be given the same energy, but the
former penetrates all the way through the game,
expending but a fraction of its energy therein,
while the latter expends all its energy therein.
Energy depends upon the weight of the bullet
and the square of the velocity, hence it is less at
long range than at the muzzle
because the velocity has fallen off at long range.
Energy is easily calculated. Simply multiply
the velocity by itself, then by the weight of the
bullet, and divide 450240 into the result.
Thus 2220 x 2220 x 170 divided by 450240
= 1860 ft. lbs., the muzzle energy of the 30-30
Winchester cartridge.
89
EROSION
The cutting or scouring out of the
steel in the barrel at the throat of the chamber
by the hot gases escaping around the bullet.
The gases in a high power rifle cartridge are hot
enough to melt steel.
90
ESCUTCHEON
Reinforcement border or
bushing through which a screw or screws, or
other fastening device, passes.
91
EXPRESS
Term usually applied to denote a
| rifle or cartridge of higher than usual velocities.
92
EXTRACTOR
Part, usually shaped in the
form of a hook and attached to the bolt or
breechblock or other part of a rifle or chamber of
a firearm. It is the part which actually extracts or
withdraws the fired case from the chamber, the
case later being expelled by the ejector.
93
FIRING PIN
The pointed nose of the hammer
of a firearm, or the separate pin or plunger which,
actuated by the hammer, or the mainspring, dents
the primer, firing the cartridge.
94
FLASH (OR CYLINDER) GAP
The distance
between the face of a revolver's cylinder and the
breech end of the barrel. U.S. industry standards
call for a gap of .006 inch, with a .003 inch
tolerance.
95
FLINTLOCK
A muzzle-loading gun fired by
means of a piece of flint, held in the hammer or
"cock" jaws, striking against a steel "frizzen".
Incandescent particles of steel scraped from the
frizzen fall into a "pan" holding powder. This
ignited powder flames through the "touch-hole"
thus firing the main charge.
96
FLOATING FIRING PIN
On a revolver, a
firing pin that is mounted inside the frame, as
opposed to being pinned to the hammer.
97
FLUTE
Groove in various types of tools such
| as reamers, drills and taps.
98
FLUX
Substance or mixture of substances
or chemicals used to facilitate the bonding of
metals together by means of soluble brazing or
welding. Fluxes are commonly made in the form
of powder, pastes and liquids.
99
FORCING CONE
The portion at the breech of
a revolver's barrel that tapers into the rifling, and
the area forward of a shotgun's chamber where
the shot is "forced" into the barrel
100
FOREARM
Portion of the stock which is
forward of the receiver and directly under the
barrel of a firearm. It is sometimes called the
fore-end, especially with respect to shotguns
wherein the stock is made up of two pieces.
While it is a separate piece in the case of a twopiece stock, it is simply the forward part of a
one-piece stock.
101
FORE-END
The forward portion of a stock
| under the barrel which serves as the foregrip.
102
FORGING
One method of working or shaping
| metals.
103
FPS
Stands for "Feet per Second," by which
| bullet velocity is measured
104
FRAME
The skeleton or framework of a firearm to which the barrel and stock are fastened
and in which the breech, lock, and reloading
mechanism are located. Also termed receiver.
105
GALLERY
A term usually applied to an indoor
| rifle or revolver range.
106
GAS-OPERATED
A system of operating an
automatic or semi-automatic firearm in which
a portion of the powder gasses is bled off from
the barrel and used to activate a piston or similar
device that cycles the breech-block, bolt, or
slide.
107
GAS CUTTING
The effect of the rushing
of powder gases past a bullet in the bore,
usually because the bullet is not large enough
to completely seal the bore. Hot powder gases
at high pressure when forced through a small
orifice have considerable cutting or erosive
effect on the sides, both of the bore and of the
bullet. This defect sometimes occurs when rifles
and ammunition are not accurately made, one
for the other. Also seen at the area above the
cylinder, on the top strap of revolvers
108
GAUGE (gage)
Term used for the
designation of shotgun bore sizes. Standard shotgun bores, ranging from the smallest to the largest, are: 28, 20, 16, 12, and 10. Old guns were
often made in 8-gauge. They are no longer being
produced in the United States. .410 is usually
referred to as a gauge, but this is really a caliber,
being the actual measurement of the bore.
109
GAUGE, SHOTGUN
The unit of measure
of the bore diameter of a shotgun. The gauge is
the number of lead balls, of the diameter of the
gun bore, that make a pound. Thus, a 12 gauge,
or 12 bore means that 12 pure lead balls of such
a diameter will weigh one pound. The standard
diameters of shotgun bores of various gauges are
as follows:
4 gauge...................... .935"
8 gauge...................... .835"
10 gauge..................... .775"
12 gauge..................... .730"
16 gauge..................... .670"
20 gauge..................... .615"
28 gauge..................... .550"
410 bore (36 gauge)... .410"
110
GRIP
Small part of the stock which is grasped
by the hand. It is also used to designate the
handle of a pistol or revolver
111
GRIP, PISTOL
A portion of a stock which
swells out, downward and to the rear in a form
approximating the handle of a pistol, or an actual
vertical grip for use by the shooter's trigger hand.
112
GRIP SAFETY
A device that prevents a
handgun from being fired unless it is firmly
squeezed.
113
GRIP, STRAIGHT
A portion of a stock which
has approximately the same diameter and shape
from front to rear for the shooter's trigger hand.
114
GROOVES
Spiral cuts in a bore which cause
| the bullet to spin as it travels down the barrel.
115
GROOVE DIAMETER
In rifled arms, the
diametrical measurement between bottoms of
grooves.
116
GROUP
A number of consecutive shots fired at
a target with constant aim and sight adjustment,
their bullet holes making a group of shots on the
target. The size of the group indicates the accu- racy with which the rifle or pistol and its ammu nition were shot, including the personal errors of
the shooters.
117
GROUP MEASURE
The distance in a straight
line between the two shots farthest apart in a
group of shots on a target. This measurement is
made from center to center of bullet holes.
118
GUARD
Term applies to the loop, usually made
of metal, plastic or horn, curving around the
trigger to protect it. It is commonly called the
trigger-guard.
119
HAMMER
Part of the gun or rifle action that
strikes the firing pin to fire the cartridge within
the chamber. Guns are sometimes referred to
as hammerless, but all guns have some type
of hammer or corresponding parts such as the
cocking piece. The word "hammer" as applied
to hammer guns refers to outside hammers
which can be cocked by hand. In some hammer
guns, the hammer is cocked when the lever
or slide is operated. Others must be cocked manually every time the firearm is fired. The
word hammerless applies to a gun where the
hammers are enclosed or concealed inside the
action.
120
HAMMERLESS
Firearms having no visible
| hammers.
121
HAND
Lever or dog which turns the cylinder
of a revolver. The hand is attached to the trigger
or hammer and when the hammer is pulled back
to cocked position, the hand is actuated and turns
the cylinder into position so the cylinder lock
can lock the cylinder prior to the next shot.
122
HANG-FIRE
Term used to describe a delayed
action or delayed ignition when the trigger is
pulled, the firing mechanism strikes the primer
of a cartridge, but nothing happens until an
instant later. It can result in a disaster or a blownup gun if the shooter does not wait long enough
to determine whether it is actually a misfire or a
hang-fire. In the event it is a hang-fire, and the
bolt or locking mechanism is opened too soon,
the cartridge can explode when it is moved partly
or completely out of the chamber, but still in the
action of the gun.
123
HEADSPACE
For rimmed cartridges, the
distance from the face of the breech block to
the barrel seat for the forward surface of the
case rim. For a rimless bottleneck cartridge,
the distance from the face of the breech block
to a predetermined point on the shoulder of the
chamber. For rimless straight cartridges, the
distance from the face of the breech block to
the shoulder or ledge in the chamber. Belted
cases headspace on the forward edge of the belt.
When head space is too little the breech will not
close on the cartridge. When there is too much,
misfires begin to occur, and the safety factor is
lowered. Excessive headspace is dangerous and
may result in serious injury.
124
HIGH BASE SHELL
An outmoded term for
a shell furnished with high inside base wad,
approximately 3/4" thick before forming. Not
needed in the compression-formed Super-X and
Super-Speed all-plastic shot shells.
125
HIGH BRASS SHELL
The highest
quality of shotgun shells in which the brass base
extends a considerable distance up on the plastic
or paper tube.
126
HIGH POWER
A dated term used to designate
a rifle or cartridge having a muzzle velocity in
excess of 2,000 feet per second.
127
HINGE
The joint in a break action, breech
| loading rifle or shotgun connecting barrel or barrels with the frame.
128
HINGE PIN
Pin upon which the barrel or
| barrels of break actions hinge.
129
IMPROVED CARTRIDGE
Form of a wildcat cartridge usually made by fire-forming the
cartridge. A factory cartridge can be fired in a
slightly altered chamber, thus blowing the case
out to create a wildcat or improved cartridge.
This means a rifle chambered for one of these
cartridges will still handle factory ammunition.
130
INERTIAL FIRING PIN
A firing pin that
is too short to contact the cartridge's primer
when the hammer is resting on it and can only
hit the primer when driven forward under the
momentum of the hammer blow.
131
JHP
Stands for Jacketed Hollow Point; a bullet
similar to a Jacketed Soft Point, except that a
portion of the nose is hollowed out for greater
bullet expansion.
132
JSP
Stands for Jacketed Soft Point, a type of
bullet with a soft lead core enclosed by a hard
metal jacket, but with the nose section exposed
to allow bullet expansion.
133
KNURLING
The checkering of metal to
| produce a rough surface
134
LANDS
Term used to describe the space
between the grooves of a rifle barrel. It also
describes the space or ridges between the flutes
on reamers and other tools which have flutes.
135
LAP
Piece of soft metal in the form of a plug or
| other shape which can be charged with abrasives.
136
LARGE BORE
In the United States, any rifle
of .25 caliber or over is termed a large bore, or
big bore.
137
LEADING
Deposits of lead left in the bore of
| a rifle or shotgun.
138
LENGTH OF STOCK
The distance in a
straight line from the center of the trigger to
a point midway between the heel and toe of
the bull plate, on the surface of the plate.
Required stock length depends upon the physical
conformation of the shooter, people of short
stature or short arms requiring shorter stocks.
Also called Length of Pull.
139
LINE OF SIGHT
The straight line passing
from the eye through the sights to the target.
Also termed the line of aim.
140
LOCK
The combination of hammer, firing
pin, sear, mainspring and trigger which serves
to discharge the cartridge when the trigger is
pulled. It is also known as the fire control or
trigger group.
141
LOCKING BOLT
The bolt used in a break
down, breech-loading gun to lock the breech
in its closed position. Also in certain repeating
rifles, the sliding blocks which lock the breech in
its closed position
142
LOCKSPEED (LOCKTIME)
The time
consumed between the releasing of the firing
mechanism and the explosion of the cartridge
143
LUBRICATION OF BULLETS
Most lead
bullets have to be lubricated with a grease
or wax placed on their surface or in their
grooves to prevent leading the bore. Externally
lubricated cartridges have the lubricant placed
on the surface of the bullet outside the case.
Internally lubricated bullets have the lubricant
placed in grooves or cannelures on the bullet and
it is concealed by the neck of the case.
144
LUG
In a breakaction, breech-loading shot gun
or rifle a lug on the barrel which secures the
barrel to the frame. Lugs located on the front of
a bolt or breech block rotate into slots to lock the
action for firing are termed locking lugs.
145
MAGAZINE
The part of a repeating firearm
which receives the cartridges, from which they
are fed into the chamber when the repeating mechanism is operated. There are numerous
types of magazines such as box, tubular, rotary,
etc.
146
MAGAZINE, BOX
One in which the
| cartridges are horizontally stacked.
147
MAGAZINE Follower
A spring-actuated
plate which feeds the cartridges or shells in a
magazine into loading position.
148
MAGAZINE, FULL
A tubular magazine
| reaching the full length of the barrel.
149
MAGAZINE, HALF
A tubular magazine
| reaching half the length of the barrel.
150
MAGAZINE, TUBULAR
One in which the
cartridges are carried end-to-end in 11 tube
located either beneath the barrel or within the
stock.
151
MAGNUM
In connection with firearms it
serves to designate rifles using extremely large,
powerful cartridges. It is also used to describe a
firearm of greater-than-average power.
152
MAINSPRING
The spring, either flat or coiled,
which provides the energy to carry the hammer
or firing pin forward to strike the primer.
153
MATCH RIFLE
A rifle explicitly designed for
competitive shooting, normally on an organized
basis.
154
MATTED RIB
A raised, solid rib along the
top length of a shotgun barrel to cut reflection
and improve sighting. See RIB.
155
M.C. METAL CASE
Form of bullet
completely covered forward with copper or
copper alloy (usually) jacket. Generally a
military bullet type, and also termed "solids",
and F.M.J. (full metal jacketed)
156
MEAN RADIUS
The scientific method of
measuring a group of shots fired on a target
from a rifle or pistol. It is the average deviation
from the centerpoint, found by adding the
measurements and dividing the result by the
number of shots.
157
METAL FOULING
A deposit of bullet-jacket
| metal left in the bore of a rifle.
158
MONTE CARLO
Form of stock in which the
comb extends horizontally or parallel to the axis
of the bore to within a short distance of the heel,
where it descends abruptly to the heel portion.
On rifles, Monte Carlo stock is popular with
target shooters for it helps them use target-type
sights which are mounted necessarily rather high
above the bore. It is also quite popular among
shotgun trap-shooters.
159
MOUNTS
Metal bases used to secure a
telescopic sight to the barrel or receiver of a
firearm.
160
MUZZLE
End of barrel opposite to breech;
| point from which bullet or shot leaves barrel.
161
NIPPLE
Tube which receives the percussion
cap of a muzzle-loading or percussion-loading
firearm. It is a small projection through which
there is an opening leading to the powder charge
in the barrel. Upon detonation, the flash from the
cap is carried through the opening in the nipple,
into the powder charge in the barrel.
162
O'CLOCK
A term used by riflemen to
indicate a location on the target or on the rifle
range, corresponding to similar locations on the
face of a clock; 12 o'clock being at the top of
the target, or at the target end of the rifle range.
Thus a shot striking the target immediately to
the left of the bull's eye is a hit at 9 o'clock, and
a wind blowing from the right at a right angle to
the line of fire is a 3 o'clock wind.
163
OLIN BALL POWDER
The big advantages
of Olin Ball Powder are: no excessive smoke
or muzzle flashing, clean burning, excellent
stability in all climatic conditions, less gun barrel
wear due to erosion, and positive lots and speed
duplications. The process of manufacturing
smokeless ball powder is one that has been
completely developed at East Alton, Illinois by
Olin Mathieson. Years of extensive research
of special trained chemists and chemical
engineers were required to perfect the process.
All smokeless powders prior to the Olin Ball
were manufactured by a method known as
the extruded powder process. It required large
bulky equipment-hydraulic presses and mixers. Ball powder is prepared in large agitated vats
equipped with condensers. The extruded process
requires from six weeks to six months before
the powder is ready for use. In the process, the
materials are handled seven or eight times. A
complete lot of Olin Ball Powder can be made
from basic raw materials in 60 hours. It is
handled only one time and this is after drying
process has been completed.
