various air craft weapons used by Fighter jets'

1. Chapter 3
INTRODUCTION TO AEROWEAPONS
FUNDAMENTALS OF SMALL ARMS

2. INTRODUCTION
 Calibre
 12.7mm or 0.5"
 up to 30mm (Cannons)
 25.4mm or 01" Calibre is the dividing line between
Light and Heavy Weapons
 At present, the category extends upto the limit of
35mm and tends towards Small Gun Calibres of
37mm - 40mm
 In a broader sense,
Small Arms are Portable, Direct Fire Weapons of
Calibre < 50mm

3. INTRODUCTION

4. Pistols
• Revolvers
Single/Double action
Break/Side opening
type
Advantages
Mechanism is simple
Safe to use
Reliable
No safety catch
Disadvantages
Reduced effectiveness
Limited capacity
• Self Loading Pistols
Semi automatic
Advantages
Magazine capacity
Ease of reloading
Compact
Silencer fitment
BNS 4

5. BNS 5
Sub Machine Guns
• Characteristics
Light weight: ~3kg
Small bulk
Handiness
Large volume of fire
Short effective range,
100 - 200m
Limited accuracy and
Penetration
Automatic with
selection choice
Silencer concept
Blowback operated
Butts: Telescopic /
Removable / Foldable
Magazine capacity
CQB Weapon

6. BNS 6
Sub Machine Guns
• Characteristics
Light weight: ~3kg
Small bulk
Handiness
Large volume of fire
Short effective range,
100 - 200m
Limited accuracy and
Penetration
Automatic with
selection choice
Silencer concept
Blowback operated
Butts: Telescopic /
Removable / Foldable
Magazine capacity
CQB Weapon

7. BNS 7
Rifles
• Hand operated
Bolt action
Weight: 4 – 5kg
Low rate of fire
Very powerful round
Sniper rifle
• Automatic
Weight: 3 – 4kg
Single / Auto / Burst fire
(TRB Concept)
Blowback /
Gas operated
• Semi automatic
High rate of fire
Semiautomatic
Magazine capacity
Effective range
Sniper rifles
Blowback /
Gas operated

8. BNS 8
Machine Guns
• LMG
Weight: 7 – 10kg
Considerable fire power
Easy concealment
Max effective range: 600m
Shoulder control with
bipod support
Single / Auto / Burst fire
Spare barrel concept
Magazine capacity: 30
rounds
High rate of fire
• MMG
Good degree of portability
Sustained fire:
400 – 450 rpm
Spare barrel concept
No single shot fire, only
auto
Range: 2000m
Tripod based belt feed
barrel cooling

9. BNS 9
Machine Guns
• HMG
Calibre:  12.7mm
Mounted on
APC, ICV, Air craft etc
Tripod mounting
Range: 3000m
Ammunition
HE and AP
No single shot
Suppressive fire
• Cannons
Calibre: 20 – 50mm
Mounted on vehicles
Ammunition
AP and HE
Anti-vehicle,
Anti-material and
Anti-personnel roles

10. Classification of Small Arms
BNS 10
Based on Power Source
Pure Blowback
Advanced Primer Ignition
Blowback with Delay or Retarded Blowback
Blowback with Locked Breech
Blowback (Spent Case Projection)
Long Recoil
Short Recoil
Recoil Operation
Long Stroke Piston
Short Stroke Piston
Direct Gas Action
Gas Operation
Internal (Self) Power (Ammunition)
Bolt Action Rifle
Revolver
Gatling Gun
Manual / Mechanical
Gatling Gun
Chain Gun
Rotating Element Gun
Electrical
External Power
Small Arms

11. BNS 11
Cycle of Operations
• A round is chambered
• The breech is locked
 except with most blowback
operated weapons
• The firing mechanism is
released
 Initiates primer
 Propellant burns
 Rapid rise of chamber
pressure
 Shot start, round gains
velocity and spin
 Shot exit
• The breech is unlocked
• The breech is retracted
• The empty case is extracted
from the chamber
• The return spring is
compressed to store energy
• The empty case is ejected
from the gun
• The firing mechanism is
cocked
• A new round is fed into
position for chambering
• The round is chambered

12. Operating Mechanisms
Energy for Automatic Operation
Powered internally (Self powered)
Source of energy from Propellant (Ammunition)
Powered externally (Outside source)
Source of energy from Electric motor or
Hand Cranking
Small Arm
Single cylinder internal combustion engine
Bullets form a series of expendable pistons
Distribution of Energy
Muzzle energy: KE of bullet : 30%
Heat to Barrel : 30%
Recoil energy : 0.1%
Muzzle gas energy : ~40%
BNS 12

13. Automatic Operation
Self Powered
Energy derived from the burning of Propellant which
is otherwise would have been wasted
 Only available for very short time
 Some form of energy storing device: Springs, moving
Masses
 Substantial forces arise due to short energy transmission
times
 Operating reliability is highly dependant on reliability and
consistency of the Ammunition
Basic Systems of Automatic Operation
 Blowback Operation (Spent case projection)
 Recoil Operation
 Gas Operation
BNS 13

14. Basic Principles
 Conditions in the chamber when a Round is Fired
Propellant burns and produces
14000 times its own volume of gas
2500K, Flame Temperature
340MN / m2, Peak Pressure
4.605KJ / gm of heat of modern propellant
Peak pressure in 0.75ms from the ignition of primer.
Rate of burning is proportional to the chamber pressure.
Just after peak pressure is the All Burnt Point (ABP).
Pressure produced drives the bullet out of the case and
into the lead.
Bullet is held in contact with the developing rifling until
sufficient pressure (shot start pressure) has built up to
engrave the envelope.
1/7
BNS 14

15. BNS 15
Pressure Time (pt) Curve

16. BNS 16

17. BNS 17

18. Basic Principles
SSP is about 0.4ms after the cap strike.
As the projectile moves out of the lead the chamber volume
increases.
Shortly before ABP the rate of increase of chamber volume is
greater than the increase in the rate of gas production, hence,
the chamber pressure starts to drop.
From the point of ABP to bullet emergence the expansion of
the gas is adiabatic.
When the bullet leaves the muzzle the propellant gases follow
it with a pressure of about 46MN / m2, accelerate and expand
rapidly down to atmospheric pressure giving a very distinct
backward impulse to the whole weapon.
The time between
cap strike and bullet exit: 1.5ms
cap strike and gas to expands to atmospheric pressure: 4 - 5ms
2/7
BNS 18

19. Basic Principles
Effect of Pressure
Acts in all the direction with
same magnitude
Bullet driving force
Obturating force by forcing
the case radially outwards
Forward force on the case:
Tapered or Bottle necked
case
Backward force
Longitudinal tension in the
case wall
Case driving force (along with
bolt): same as bullet driving
force
3/7
BNS 19

20. Blowback Operation
Blowback is a method of operation in
which the energy required to carryout the cycle
of operations, is supplied to the bolt by the
backward movement of the cartridge case,
caused by the gas pressure
Types of Blowback
Pure or Simple Blowback
Blowback with API
Retarded or Delayed Blowback
Blowback with locked Breech Block
BNS 20

21. Simple Blowback
 Operation
Breech block is stationary at the instant of firing
Gas pressure forces the bullet and breech block to move
simultaneously
The operating energy and movement of the cartridge case is
restrained and controlled solely by the Mass / Inertia of the
breech block, Stiffness of return spring and frictional force
 The restraining force is very important from the point of safety
 Usage of low powered ammunition and barrel length is reduced in order to
minimise the period of high pressure
 Reduced muzzle velocity, range and accuracy are generally inadequate for
battlefield
The bolt and cartridge case accelerates because of action of
blowback force
Accelerating force becomes zero on complete expansion of
hot gases to atmospheric pressure, the breech block with case
continues to move due to acquired momentum
1/3
BNS 21

22. Simple Blowback
Cartridge case extracts from chamber and ejected out
Bolt slows down as the resistance of the return spring,
the frictional force and cocking losses
Return spring forces the breech block forward, and
new round is chambered
Characteristics
Unlocked breech
Heavy inertial type breech block
Simplicity
Strong return spring
Parallel sided cartridge case
Poor accuracy
2/3
BNS 22

23. Simple Blowback
Design requirements
Weight of the breech block is so calculated that, it
does not permit its movement more than 3mm in
05ms
Mean velocity slightly over 0.6m/s
Requirement of heavier breech block with return spring
Employment
Limited: Suitable only for low powered rounds of
small calibre and restricted to pistols
Sporting pistols and rifles of 0.22 calibre
Military weapons: 9mm Makarov (Russian)
9mm Stechkin (Russian)
7.65mm Skorpion (Czech)
3/3
BNS 23

24. Gas Operation
This is the method of operation in which
the energy required to carryout the cycle of
operations is obtained by ducting off expanding
propellant gases to force back the working
parts
BNS 24

25. BNS 25

26. BNS 26
Gas Operation

27. Gas Operation
 Factors involved in tapping the gas off
Near the Muzzle end:
 Minimum effect on ballistics
 Large volume of gas to carryout required task
 Less erosion of gas port
 Long linkages
 Increased carbon fouling
Near the Breech end:
 High pressure gas: Requirement of robust parts
 Earlier unlocking (Short delay before unlocking): high
rate of fire
 Increased erosion of gas port
Position of gas port has a significant effect on design and
performance of the weapon
Exact location depends on “Power required to provide
Acceptable Rate of Fire without incurring either
Unacceptable Erosion or Carboning up (Fouling).
2/9
BNS 27

28. Gas Operating System
 Essential elements
 Piston, bolt, bolt locking and unlocking arrangement, return
spring, back plate buffer
 In large calibre guns, e.g.. 20mm: Recoiling forces are large
 Additional arrangement to allow recoiling of barrel and bolt or
entire weapon with in a buffered cradle
3/9
BNS 28

29. Gas Operating System
 Cycle of operation
 Round chambered, bolt locked to barrel extension or
gun body
 On firing Projectile is driven forward, Recoiling parts
move back (usually entire weapon)
 Time of port opening after the cap strike:
0.75 - 1.5ms Rifle calibre, upto 2ms 20mm
 Cylinder pressure: 1/3 barrel pressure
 Deliberate design feature of a period of free travel of
piston before the unlocking of bolt commences, to
allow bore pressure to drop to a safe operating limit
Bullet will be well clear off the muzzle when unlocking occurs
 Residual pressure (Blowback action) + force on piston
accelerate the bolt, bolt + piston moves rearward
 Normal cycle of operation is carried out
4/9
BNS 29

30. Gas Operating System
 Direct Gas Action
 No piston
 Gas is tapped off from the barrel, taken along the
tube to act directly on the breech mechanism
 Gas is fed into a chamber between the bolt and the
bolt carrier, forces the bolt carrier backwards,
unlocks the bolt and trusts it backwards
 Employment : Madsen - Ljungman
French MAS 44
AR 15 or M 16A1
 Light, simple and cheap system
 Carbon fouling: Liable to incur stoppages
Chromium plated chamber and barrel
9/9
BNS 30

31. Gas Operation
Control of operating energy
~40% of propellant energy is available
More gas to the piston head
Shorter the time of cycle of operation
Increased rate of fire
Insufficient gas to the piston head
May drive the piston back sufficiently to allow
extraction, ejection and feed and
May not give sufficient backward movement on
release of trigger
Gun may continue firing as sear may not engage
the bolt
Run away gun results
1/5
BNS 31

32. Gas Operation
Control of Rate of Flow of Gas
The amount of gas needed to operate the weapon varies
according to the battlefield conditions
Gas port should only be adjusted in order to maintain the
correct cyclic rate of fire
Different ways
Variable size gas track
Variable exhaust to atmosphere
Constant Volume system
Variable expansion volume
Variable Size Gas Track
Oldest and simplest method
Gas regulator with a number of tracks each of different size
Manual control
Employment : LMG - 4 Tracks
Guryunov M43 (Russian MMG) - 3 Tracks
2/5
BNS 32

33. Variable Gas Track
Variable Exhaust to Atmosphere
Gas Operation
Variable Exhaust to
Atmosphere
More energy is available
than generally be
required
A fairly large hole drilled
in the barrel
Partially gas escapes to
atmosphere, remainder
used for gas operation
Variation in rate of fire
through control of gas
vent to atmosphere
Employment : SLR
FN Rifles
MAG
GPMG L7A2
700 - 1100rpm
3/5
BNS 33

34. Constant Volume Regulator
Variable Expansion Chamber
Gas Operation
Constant Volume System
 Self regulating system, no firer
control required
 Hollow piston with a groove
connecting a number of holes
 Short stroke gas operation
 To fire various natures of
ammunition with different gas
pressure at the barrel vent
 Constant Energy System
 Employment: US M60 GPMG
Variable Expansion
Volume
 Variable gas pressure by change
in volume of cylinder
 Not used in modern weapons
 Employment: Hotchkiss MG
4/5
BNS 34

35. Gas Operation
Advantages
Flexibility : In obtaining varied impulsive power on piston
to carryout cycle of operation
Light weight : Selection of correct gas pressure enables the
working parts to be lightly constructed
Rate of fire : Very high rate of fire
Accuracy : Light parts, little change in position of cg,
minimum vibrations caused by locking, fixed
barrel relative to the gun body
Ammunition: Mix of ammunition with varying gas pressure
Disadvantages
Fumes : Not suitable for enclosed space
Erosion : Increased gas flow, local irregularity in the bore
Carbon : Fouling, clogging - Special arrangements:
Vented cylinders, Exhausting Systems
Temperature: Cyclic rate of fire varies with temperature
5/5
BNS 35

36. Basic Principles
No use is made of any propellant power
Old bolt action rifles, revolvers used power
provided by firer himself to reload
New guns added electrical motor to replace human
effort
Advantages
Once loaded can be operated remotely
Due to the dwell time extremely low level of toxic fumes
expected in turret
Better reliability. Rounds fired for any reason are
cycledthrough the gun and ejected.
External Power 2/7
BNS 36

37. Gatling Gun
Designed to fire at high cyclic rate of fire
A number of barrels which are rotated and fed by an external
source
Each barrel has its own bolt which locks into the barrel
extension
Each bolt has its own firing pin
Each Barrel-Bolt performs independent cycle operation
Firing at 120' clock position
Vulcan 20mm Cannon, 7.62mm Mini Gun: 6000rpm
Aircraft Gun and Antiaircraft role
Misfires are ejected with the empty cases, no stoppage
of fire is involved
A hang fire ejected like a misfire and could cause
serious damage
External Power: Revolver Gun2/7
BNS 37

38. Gatling Gun
BNS 38

39. Gatling Gun
BNS 39

40. External Power
Gatling Gun
Advantages
High Rates of Fire
Low Barrel Heating and Wear
Simple Mechanical Design
Light in Weight for Specific Muzzle Power
Disadvantages
Requires Large External Power Source
Large and Complex Feed Mechanism
Requires Large Quantities of Ammunition
Relatively Large Dispersion
Shift in the Mean Point of Impact during acceleration
of the Barrel Group from Rest
3/7
BNS 40

41. External Power
Chain Gun
Calibre: 7.62mm to 30mm
Single Barrel
700rpm
Cycle of movement
 Four Sprockets
 Duplex Endless Chain
 Sliding Member
 Slotted Breech Carrier
 Transverse movement of Sliding Member
 Dwell: Firing, Feeding
 Multi Lugged Rotating Bolt
Hang Fire
 Recoil Sensor Interlock
 400rpm maximum
4/7
BNS 41

42. Chain Gun
BNS 42

43. Chain gun cycle of Operation
 Chain follows a rectangular path around sprockets . It has a
master link that connects to the feed, ram and ejection parts
 The gun cycle continues after the trigger is released and always
park in open or safe position.
 The bolt is locked to the barrel extension by rotation of twin
lugs moved through 40 degrees by a cam. These lugs also form
twin fixed extractors.The firing pin can not protrude untill the
bolt is locked in position.
External Power 2/7
BNS 43

44. BNS 44
Chain Gun

45. External Power
Chain Gun
Advantages:
Low Weight, Short Overall Length and Compact Design
Variable Rates of Fire
Simple Mechanical Design
 Reliable
Disadvantages:
Requires External Power Source
Delay of Two Cartridges
 when Changing Ammunition Natures
Ejection in Three Directions
 with Dual Belt Feed
Reduced Rate of Fire
 With Hang Fire Detection: Recoil Sensor
Employment: 25mm M242 Chain Gun,
30mm M230 Chain Gun (Apache attack Helicopter)
5/7
BNS 45

46. Feed Systems
Functions / Stages
The holding device which presents the ammunition
to the weapon and transfers it to the feed
mechanism
Magazine, Belt, Strip
The feed mechanism which takes the round from the
holding device and positions it for loading
Gun driven, Spring driven, External Source driven
The final process of loading the round into the
chamber
Breech block
Actuating link (Rammer): USA M73 Tank MG
Hopper feed system: Nordenfeldt Machine Gun
BNS 46

47. Holding Devices
Magazine
Box
Drum
Gun driven
Spring driven
Tubular
Strip
Flat
Articulated
Belt
Fabric with metal
strips
Fabric (Stripless)
Metal
Metal cum fabric
Metal disintegrating
link
1/6
BNS 47

48. Holding Devices
Magazine
Box
Drum
Gun driven
Spring driven
Tubular
Strip
Flat
Articulated
Belt
Fabric with metal
strips
Fabric (Stripless)
Metal
Metal cum fabric
Metal disintegrating
link
1/6
BNS 48

49. Holding Devices
Effect of weapon roles
The role of the weapon dictates which of holding
devices is preferred:
Method of attachment to the weapon
Number of rounds immediately available in any one
system
Method of carriage and supply
Serviceability
Magazines: Box type
Straight or Curved sided
Essential parts: Casing, Spring, Platform or follower
Column loading: Single or Staggered
2/6
BNS 49

50. Magazines
BNS 50
Box Magazine

51. Holding Devices
Design features / considerations
Essential to ensure the correct functioning of the
feed system, and in turn, the efficiency of the gun
 Control of displacement of
rounds in staggered columns
Width of case
Shape of follower
form of lips
 Fullering
Reduced friction
Clearance space for ingress of
dirt, mud, sand…
Strengthens the magazine
body
 Angle of presentation
Lips of magazine
Round feeds forward into the
chamber without jamming
 Platform spring
Must be strong enough to feed the last
round up when nearly extended, but not
too strong when fully compressed
 Magazine attachment device
Easy fitment and removal of magazine
Rigid support / hold of magazine in
position to avoid variation in angle of
feed of rounds
 Position of magazine fitment
Above
Below
Side
Along the barrel
3/6
BNS 51

52. Magazines
Drum Magazine: Saddle or Double drum
Drum Magazine: Spring driven Drum Magazine: Gun driven
4/6
BNS 52

53. Feed Mechanisms
Feed mechanism takes the round from holding device and
positions it for loading
Types
 Gun driven
 Spring driven
 External source driven
Gun driven feed
mechanism
 One of the reciprocating
parts of the gun will give the
required energy during the
normal operating cycle
Bolt,
Barrel extension
or Side plate
1/6
BNS 53

54. Feed Mechanisms
 Design factors: Gun driven feed mechanisms
Type of feed system to be used
Amount of energy required to drive the mechanism for
the feed
Amount of energy that can be provided by the type of
operation for the particular gun
Cyclic rate of fire
Number of rounds and weight of conveyor required to
be moved and lifted by the feed mechanism
Whether any external source of energy available for
assisting the feed mechanism
Type of conveyor: Open or Closed, Belts or
Disintegrating links
Type of ammunition: Alternative feed
Weapon role
5/6
BNS 54

55. Feed Mechanisms
Spring Driven Feed Mechanisms
Operating energy from spring
Spring energy is replenished by the gun
Dirt, dust etc increases the frictional resistance
No extra reserve energy
20mm Hispano, Manlicher Schorenaur rifle
External Source Driven Feed Mechanisms
Any available source of energy
Electrical, Mechanical, Hydraulic or Pneumatic
Weapons of Tanks, Aircrafts and Boats
Gatling Gun, Chain Gun
6/6
BNS 55

56. Extraction
Extraction is the process by which the fired case or
unfired round is withdrawn from the chamber
Primary Extraction
Initial movement of the fired case, after it no
longer grips on the chamber wall, thereby
ensuring rapid and smooth extraction
Additional leverage or mechanical advantage in
the mechanism such as cam shaped locking
lugs(incorporated in the unlocking action)
 Ease of extraction
Lubrication make extraction easier but it collects dirt and
therefore unacceptable in most service roles.
Fluted chamber is also used with high rate of fire weapons
BNS 56

57. Extraction
Design Considerations
Operating chamber pressure > 340 MPa
Both cartridge case and chamber wall expand radially
outwards under the action of gas pressure
Yield strength of barrel material >> Yield strength of
cartridge case
The cartridge case of thin section will follow the expansion
of the steel chamber, which will restrict its dilation
Chamber, after expanding, will revert to its previous
dimensions, not having exceeded its elastic limit but,
Cartridge case may or may not return to its original
dimensions
Initial clearance between the chamber wall and cartridge
case
To allow the case to enter the chamber
Permanent setup of cartridge case > initial clearance
Interference: Extraction is difficult or sometimes impossible
1/5
BNS 57

58. BNS 58

59. Extractor
Extractor
Attached to the face of the breech block
Operated by the action of reciprocating parts
Functions:
To engage behind the rim or groove
To pull cartridge case out of chamber
Extractors need to be strong but small
Contradiction in requirements, leads to failure:
Requirement of spares
Type of Extractors
One piece claw
Multi piece claw
‘T’ Type
Combined Extractor-Ejector
Integral with breech face
3/5
BNS 59

60. Extractor
BNS 60
Single Piece Claw Extractor
Multi Piece Claw Extractor

61. Ejection
Ejection is the process by which the extracted
case or unfired round is removed from the
feed way
Type of Ejectors
Fixed or Pivoted in bolt way
Rocking Type
Push Rod Type
Combined Extractor-Ejector
Two Stage Ejector
BNS 61

62. Ejector
BNS 62

63. Firing and Trigger Mechanisms
Firing Mechanism
is the means by which energy is supplied to the
cap to initiate it
Types
Percussion Type : Mechanically operated
Electric Type : Bridge wire
: Conducting cap composition
Trigger Mechanism
is the mechanism by which the firing mechanism
is controlled
BNS 63

64. Firing Mechanism
Percussion Type
Impulsive blow on cap to supply enough energy to
initiate the cap
0.395J in the case of 7.62mm NATO Round
A Striker or Firing Pin
A mechanism to provide energy to the striker or firing pin
Firing Pin
Striker
2/6
BNS 64

65. Firing Mechanism
Firing Pin
The energy supplied is from a separate source
(within firing mechanism)
Spring operated Hammer
Types
Free Floating firing pin
Spring retracted firing pin
Design aspects / considerations
Unintentional initiation of cap, when the weapon swung violently
Pierced caps
 Excessive protrusion of pin
 Excessive striker energy
Breaking or Bending of firing pin
 Improper tempering
Cap perforation and blowing of high pressure gas
 Inadequately supported cap: The firing pin / striker must remain in
contact with the cap and must be adequately supported as the chamber
pressure rises
3/6
BNS 65

66. Firing Mechanism
Striker
The energy supplied is either from
(outside the firing mechanism)
A spring which is permanently associated with the striker
Utilising the kinetic energy of some mass to which striker is
attached
 Bolt of SMG
Design aspects / considerations
Form and Mass
 To provide sufficient energy
Robust
 To allow for some degree of eccentric strike loading
Controlled penetration in to the cap
 To prevent piercing of cap and gases to escape causing damage
and erosion
Blunt nosed striker gives a better transfer of energy and
crushing effect to the cap with more positive and efficient
ignition of the cap composition
4/6
BNS 66

67. Trigger Mechanism
Trigger mechanism consists of mechanical linkage or the
electric device which controls the firing mechanism
Primary Functions
Initiate the train of events which cause the firing
mechanism to operate and fire a cartridge
Control the length of burst fire
Single round, Three round, Auto
Ensure that the working parts are brought to rest in the
correct part of their cycle and reopen the fire as and when
required
A trigger mechanism can only be effective when the
weapon is cocked and ready for firing
Trigger mechanism never provides the energy necessary
to operate the firing pin, excepting in the case of some
electric impulse trigger mechanisms and revolvers
Trigger mechanism controls the release of energy to
operate the striker when it is desired to fire the weapon
5/6
BNS 67

68. Cook Off
The unintentional firing of a round due to the
propellant becoming too hot
 firing of bullet in unintended direction. Misfired
round may cook off and the case may burst , while
being extracted from chamber.
Time taken for cook off for a given chamber wall
temperature depends on:
The chamber wall thickness
The chamber design, e.g. Fluted
The type of propellant
The cartridge case material
The cartridge case thickness
The air space and cooling effects around the barrel and
body
5/5
BNS 68

69. Electric Trigger and Firing Mechanisms
Electric Trigger Mechanisms
When used in conjunction with mechanical firing
mechanisms
Simply a remote control trigger device
Signal to start or stop firing to the mechanical sear
Simple electric mechanism: Electric coil and plunger
Very light mechanism for remote control
Simple to embody an applied safety
When used in conjunction with electrical firing
mechanisms
Same effect as with mechanically operated firing
mechanisms
Firing mechanism itself is largely simplified
 Ammunition contains the electric igniter device in its cap
Reduce lock time to virtually zero if required, eliminating
many complicated mechanical components
Reliable if correctly designed
Often used on Aircrafts
BNS 69

70. Sights
A sight is an aiming device used to assist
in visually aligning ranged weapons with the intended
target.
Sights can be a simple set or system of markers that
have to be aligned together with the target or optical
devices that allow the user to see a sometimes
optically enhanced image of the target aligned in the
same focus with an aiming point.
There are also sights that project an aiming point (or a
"hot spot") onto the target itself, such as laser
sights and infrared illuminators on some night vision
devices.
BNS 70

71. Sights
Weapon Sights
Aiming / Sighting System
Means of aligning the Weapon with the Target
Basic Purpose
is to allow the Weapon to be pointed at the
Target
by directing the Axis of the Bore of the
Weapon so that the Trajectory of the
Projectile crosses the
Line of Sight to the Target at the required
Range
Sighting Systems are either Direct or Indirect
BNS 71

72. Direct Sighting System
Direct Sighting System
used on Direct Fire Weapons and
the line of Sight is directed onto the Target
Corrections
Elevation Correction for Range and
Deflection for Wind or Movement Target
BNS 72

73. Accuracy of Aim
Accuracy of Aim depends on
Conditions under which the Weapon is being
used, and
Type of target and lighting conditions
maximum Field of View while Aiming is important
when Viewing Target
Thus, a Sight Picture
which will merge with the background is desirable
with a minimum of
Surrounding Frame and
Obscuration from Graticules and Sight
Protectors
BNS 73