Auto Ops II PDF

AUTO OPS - II  AIM TO ACQUAINT THE CLASS WITH THE PRINCIPLES OF AUTOMATIC OPERATIONS IN SMALL ARMS  BASIC CYCLE OF OPS Fire Lock Unlock Load Extract Feed Cock Eject MANUAL ACTION  AUTOMATIC ACTION - O...

AUTO OPS - II  AIM TO ACQUAINT THE CLASS WITH THE PRINCIPLES OF AUTOMATIC OPERATIONS IN SMALL ARMS  BASIC CYCLE OF OPS Fire Lock Unlock Load Extract Feed Cock Eject MANUAL ACTION  AUTOMATIC ACTION - ORIGIN Gunpowder Excess smoke, stoppages and fouling Sir Fredrick Abel - Smokeless powder/ Cordite Water cooled brl - - 1889 - and removed the problems of Gatling Tripod mtd Gun Recoil Op cycle of ops - idea existed since 1870s but implemented in Maxim Gun - Hiram Stevens Maxim in 1884 - Maxim First fully auto machine gun Belt Fed with 600 Rds per min RoF and eff rg 1800 mtr  PRESSURE-TIME CURVE Incr in Peak Incr in volume Expansion ABP pressure pressure in behind bullet of gases Muzzle exit Pressure drop to safe lvl Pressure drop ambient Dead Time Cap Ignition of Bullet struck propellent ejected  ENERGY ENER GY Propellant gases motion - 03% Frictional losses - 03% Heat loss to Wpn & projectile - 20% Heat retained by propellant gases - 42% Projectile motion - 32% Rotational energy - 0.15% (Med Cal) Recoil motion - 0.02 - 0.50% ENERGY SOURCES ENERGY TAPPING AUTOMATIC ACTION TYPES OF OPS  PREVIEW PREVIEW 1 BLOWBACK SYS OF OP 2 3 GAS SYS OF OP KEY TAKEAWAYS KEY TAKEAWAYS 1 Revision of Automatic Operations, design of components & processes 2 Details of different sys of op 3 Consider designing a wpn sys yourself! PART I : BLOWBACK SYS OF OPS  ENERGY ENER GY Propellant gases motion - 03% Frictional losses - 03% Heat loss to Wpn & projectile - 20% Heat retained by propellant gases - 42% Projectile motion - 32% Rotational energy - 0.15% (Med Cal) Recoil motion - 0.02 - 0.50%  BLOWBACK SYS OF OPS Definition of Blowback Sys of Ops: “A method of Operation in which energy required to carry out the cycle of operations is supplied to the Bolt by the backward movement of the Cartridge case”  BLOWBACK SYS OF OPS Definition of Blowback Sys of Ops: “A method of Operation in which energy required to carry out the cycle of operations is supplied to the Bolt by the backward movement of the Cartridge case” COCK FIRE  BLOWBACK SYS OF OPS Energy reqd to carry out the cycle of ops is supplied directly to the bolt Cart case acts like the piston (Free/ restrained)  BASIC REQMT Case free to mov Case held till the time pressure is high  BLOWBACK SYS OF OPS  Firing  Actions till Obturation  Actions Post Obturation  Blow back - Cycle of Ops PRINCIPLE  TYPES COCK FIRE BLOWBACK SYS OF OPS  SIMPLE BLOWBACK Bolt Recoil spring Recoil spring & bolt mass prevents rearward mov of case SIMPLE BLOWBACK SIMPLE BLOWBACK 7.65 mm SA VZ61 Skorpion SMG AGS-17 ‘Plamya’ MEASURES TO CONT BLOWBACK FORCE Parallel Cart Case Hy Breech Block, Low Powered Strong Returner Amn Spring, Brl length Parallel Chamber  DISADVANTAGES Hy Bolt & Spring Less Rg Ltd Accuracy Wear & Tear BLOWBACK SYS OF OPS BLOWBACK WITH API Rd fired while being chambered API slowdown and stop breech block Blowback forces push breech block rearwards Breech block wt reduced CYCLE OF CYCLE OFOPS OP  9 mm CMG  No action of Lock and Unlock  CHARACTERISTICS  Bolt still mov fwd when rd is fired (API)  Unlocked Hy Bolt  Parallel sided chamber and cart case  Low powered amn  Shorter brl  Poor accuracy – shift in CG  Susceptibility to variation in amn impulse BLOWBACK WITH API 9 mm CMG Oerlikon 20 mm cannon  DANGERS IN API Early firing Late firing Hand chambering Obstruction in chamber/ oversized rd BLOWBACK SYS OF OPS BLOWBACK WITH DELAY Delay created through Mech Disadvantage Resistance to blowback force Pressure drop to safe level Two Part Bb  Lever  Roller LEVER-DELAYED BLOWBACK 5.56mm FAMAS (Clarion) ROLLER-DELAYED BLOWBACK H&K (M)G3  ADVANTAGE Simple design Cheap Robust  DISADVANTAGE Hy breech block Lesser MV (rapid incr in chamber volume) Not very safe (fumes) No means of adjusting power Precision amn COMPARISON  MISC Gas Delayed Blowback – H&K P7 Headspace Actuated Blowback – UARC autorifle Blowback with locked breech -.30 in Johnson LMG PART II : RECOIL SYS OF OPS  ENERGY ENER GY Propellant gases motion - 03% Frictional losses - 03% Heat loss to Wpn & projectile - 20% Heat retained by propellant gases - 42% Projectile motion - 32% Rotational energy - 0.15% (Med Cal) Recoil motion - 0.02 - 0.50%  RECOIL SYS OF OPS Recoil Sys of Ops: “A method of operation in which the barrel is free to recoil within the body of the weapon and is locked with the Breech/ Bolt; which is acted upon by the reaction forces generated due to forward movement of the bullet (recoil) and this movement of Barrel and Breech Block is the source of energy to complete the cycle of operation”  RECOIL SYS OF OPS  Technically, recoil is the result of conservation of momentum Fwd momentum balanced By opposite gained by projectile momentum exerted and exhaust gases back on the gun  Forces that act on the bullet will cause all or a portion of the firearm to mov backwards  Non recoil op wpns - force felt by the entire firearm  Recoil op wpns - portion of the wpn recoils while due to inertia, bal wpn remains motionless relative to ground, a gun’s mount or the firer CHARACTERISTICS Force pushing bullet also exerts pressure on bolt Free moving brl with bearings Bolt secured/locked to brl Bolt and brl mov backwards Brl unlocking mechanism Return spring - fwd push to bolt RECOIL SYS OF OPS  RECOIL SYS OF OPS Short Recoil Brl and bolt do not mov the entire rearward length together RECOIL Long Recoil Brl and bolt mov the entire rearward length together LONG RECOIL  LONG RECOIL  Start of cycle 1. - rd fired  Brl and breechblock mov back completely together  Brl returns, bolt held back (cart case extracted & ejected)  Bolt released - feed, load and lock  Ready to fire next rd LONG RECOIL - COMPONENTS  LONG RECOIL 1. Normal Normal posn posn Rd rests in chamber Compressed Bolt rel mech  LONG RECOIL 1. Bolt and brl unlocking Compressed Compressed Energy of bolt and brl tfr to return spring (more) and brl spring (less) Compressed KE to PE  LONG RECOIL 1. Energy in springs tfr to brl PE to KE  LONG RECOIL 1. PE of return spring tfr to Feed, load and lock bolt Feed, load & lock Normal posn Spring returning to normal  LONG RECOIL 1.  LONG RECOIL - CHARACTERISTICS  Brl and breechblock 1. locked and travel entire length together rearwards  Extraction and ejection in fwd mov  Very slow rate of fire  No fumes in body of wpn (APC)  Reduced stress on wpn (relatively)  Inaccurate (large change in CG)  Expensive brl bearings, complex mech  Negligible wear & tear LONG RECOIL LONG RECOIL SHORT RECOIL  SHORT RECOIL  Start of cycle - rd fired 1.  Initially both bolt and brl mov rearward  Bolt unlocked from brl at the time safe pressure achieved  Momentum of bolt rearwards gets completed Travel enough for extraction and ejection  Brl rebounding from recoil buffer/brl spring and bolt from back plate buffer/return spring  Feed, load , lock and ready to fire SHORT RECOIL - COMPONENTS BOLT BOLT RETURN SPRING  SHORT RECOIL 1. Normal posn Normal posn Rd rests in chamber  SHORT RECOIL 1. Brl and bolt unlocked Compressing Compressing Brl contacts Bolt accelerates accelerator rearward  SHORT RECOIL 1. Brl nearing Blowback force halt (some extent) Compressing Compressed Accelerator Bolt accelerates action complete rearward  SHORT RECOIL 1. Brl brought Bolt travel - extraction to a halt and ejection Compressed Expansion starts Bolt reached rear limit and rebounds  SHORT RECOIL 1. Feed, load and lock KE of Bolt Fwd travel Feed, load and lock Absorbed by buffer at rear Near normal posn Spring returning to normal  SHORT RECOIL  Locked hy brl and breechblock  Brl and bolt don’t mov the entire length together  Extraction, ejection in rearward mov  More stress on gun  Partial fumes come into the body  More accurate than long recoil  Rd maybe fired before brl runs out  High ROF (high recoil velocity)  SHORT RECOIL – HIGH RATE OF FIRE  High recoil velocity of bolt and brl Separated masses - more velocity than that of a combined mass  Blowback assistance Assistance from blowback by cart case after unlocking of bolt and brl  Accelerator eff  RECOIL INTENSIFIER - NEED  For sustained and hy fire  Low energy avbl - recoil energy is 0.02 to 0.5 %  Brl and bolt need to be hy gen - addl source reqd Large size brl, Hy bolt hd, lock brl extn for heat mech to sink in withstand force sustained fire of gas pr  Incr recoil velocity of brl, tfr of more KE to bolt SHORT RECOIL 7.62MM MG3 GPMG  ADVANTAGE  Reliable 1.  Robust  Negligible fouling  Simple brl change  No/ Partial Fumes  Suitable in AFVs  DISADVANTAGE  Lack of energy  Slow rate of fire  No means of adjusting power  Lesser accuracy of wpn  Complicated design  COMPARISON Characteristics Long Recoil Short Recoil 1. Rearward travel Complete dist Short dist Extraction/ Ejection Fwd travel Rearward travel Feeding Fwd travel Fwd travel Rate of fire Lower Higher Accuracy Poor More accurate Fumes Negligible Partial PART III : GAS SYS OF OP  ENERGY ENER GY Propellant gases motion - 03% Frictional losses - 03% Heat loss to Wpn & projectile - 20% Heat retained by propellant gases - 42% Projectile motion - 32% Rotational energy - 0.15% (Med Cal) Recoil motion - 0.02 - 0.50%  GAS OPERATION – WHY? Large amt of energy available for tapping In the form of gas pressure in brl Flexibility in energy tapping amt Regulate the energy tapped Firing uphill Clean brl Dirty brl More energy less energy more energy than lvl firing  GAS SYS OF OPS Once rd is fired, high pressure gases are formed A portion of these gases is tapped at a particular pt & used to op the working parts of the wpn sys  GAS SYS OF OPS Energy for cycle of ops obtained from that which otherwise would be wasted at the muzzle Little eff on velocity of the bullet  IDEAL LOC OF GAS VENT Effect on ballistics (dwell time) GAS VENT After ABP  IDEAL LOC OF GAS VENT Effect on ballistics GAS VENT After ABP LOC OF GAS VENT NEAR MUZZLE Low pr gas - larger gas vent Longer piston - incr wt of wpn Resublimation Long cycle of op - slow ROF Min eff on MV & ballistics Mech safety simpler LOC OF GAS VENT NEAR CHAMBER High pr gas - robust & hy mov parts Incr wt of wpn Unburnt particles - incr fouling Shorter cycle of op - high ROF Affects MV & ballistics Mech safety complicated  CONT OF GASES Variable intake Gas Regulator Fixed intake/ variable exhaust Constant volume regulator VARIABLE INTAKE Oldest & simplest Gas regulator fixed with gas vent Rotating the reg - align diff sized gas tr with gas vent Gas enters through different gas tr of diff size 7.62 mm BREN LMG VARIABLE INTAKE Oldest & simplest Gas regulator fixed with gas vent Rotating the reg - align diff sized gas tr with gas vent Gas enters through different gas tr of diff size 7.62 mm BREN LMG FIXED INTAKE/ VARIABLE EXHAUST Energy avbl >>> energy reqd Constant vol of gases enter through gas vent Gas escaping can be varied Less gas escaping , more pr on piston 5.56 mm INSAS FAMILY FIXED INTAKE/ VARIABLE EXHAUST Energy avbl >>> energy reqd Constant vol of gases enter through gas vent Gas escaping can be varied Less gas escaping , more pr on piston 5.56 mm INSAS FAMILY CONSTANT VOLUME Self reg sys with small gas vent Gas enters hollow piston which moves rear - strike the op rod cont the bolt Vent alignment broken on mov - valve shut off, gases escape to atmosphere Wpn firing varied type of amn M-60 GPMG CONSTANT VOLUME Self reg sys with small gas vent Gas enters hollow piston which moves back - strike the op rod cont the bolt Vent alignment broken on mov - valve shut off, gases escape to atm Wpn firing varied type of amn M-60 GPMG TYPES  TYPES Short Stroke Piston Piston is separated from breechblock/ bolt carrier PISTON Long Stroke Piston Piston is permt connected to the breechblock/ bolt carrier 20  SHORT STROKE Piston separated from BB carrier/op rod Piston taps/imparts momentum to BB carrier/op rod Piston at rear limit - seals gas which mov back into bore Piston returns to original posn with it’s spring - independent cycle Wt saving - shorter the stroke, nearer the gas must be tapped, near the breech SHORT STROKE  LONG STROKE Piston permt att to BB carrier Piston mov - initially no eff as BB locked Return spring aligned with piston Piston controls the position and velocity of the bolt in the op cycle  COMPARISON Short Stroke Long Stroke Does a tapping action and imparts Travels entire dist with mov parts momentum to mov parts Less robust, shorter operational life More robust, longer life Less disruption in POA, change in Disruption in POA, change in CG CG being less being more Piston has independent cycle Piston is in main cycle of op Eg. 7.62 mm SLR, 7.62 mm DSR, FN Eg. AK series, 5.56 mm INSAS Rif SCAR TYPES DIRECT GAS IMPINGEMENT No piston No gas reg Gas directly acts on mov parts Lt wt & simple design More fouling M16, SIG 716 AR  COMPARISON Direct Impingement Piston Driven Cheaper/ dirtier/ hotter/ lighter Costlier/ cleaner/ cooler/ heavier Less disruption in POA, change in Disruption in POA, change in CG CG being less being more Eg. M4 (14.5”) Eg. H&K 416 (10”)  ADVANTAGE Energy regulation - flexibility Lt wt High rate of fire Accuracy (lt mov parts)  DISADVANTAGE Fumes. Unsuitable for APC /Tk Carbon deposit Erosion of gas vent (hot gases) Brl change difficult/slow Characteristic Blowback Recoil Gas 1. Safety Unsafe Safe Safe Wt Hy Hy Lt Accuracy Inaccurate Inaccurate Accurate Rate of fire Ltd Ltd-high High Cost Cheap Costly Costly CONCLUSION JAI HIND