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Propellants, Firearms, and Ammunition Development (Evolution of Firearms…

- - - - old method: charcoal, sulfur, and potassium nitrate
      - type of charcoal makes a difference - willow wood highly valued; affects power, ease of mixture, and cleanliness
      - varying component ratios changes type of powder and usage
    - - issues of powder separating during transport, leading to degredation
      - solution: add little bit of water during grinding (called corning); potassium nitrate soluble, making it sticky; acted as binder to hold other components together; reduces dust and reduces hazard of blending and grinding
      - corned powder pressed into cakes, dried, and crumbled into granules; more powerful than dry mixture
      - size of granules determines rate of power; sorted by size via sieve; larger granules slower to release energy; can choose granule size for different purposes
    - - energy proportional to volume; need a lot for a large blast; not practical for repeating firearms
      - limited velocity due to limitation of energy per unit volume and cartridge size
      - volumetrically inefficient; only 45-55% of volume contributes to gas production (and thus propulsion)
      - produces thick smoke
      - residue corrodes steel - wears firearms
      - solutions: modern replica black powder, Pyrodex; made to fix transportation costs and storage problems of black powder
  - - - looked at oxidizers to avoid problems presented by black powder
      - use oxidizers and remove sulfur to prevent corrosive by-products
      - higher temperatures required to reduce smoke
    - - invented 1845-1846
      - treated cotton with nitric acid - adds nitrogen and oxygen to cellulose
      - better combustion if prepared with sulfuric acid, which removes excess water and allows maximal attachment of nitrate molecules
      - the treated cotton releases much more energy due to the added oxygen and nitrogen
      - produces large amount of gas and little by-product
      - reduced residue and self-contained oxidizer, but difficult to control; burning too violent for guns
    - - dissolved guncotton in alcohol and ether
      - used to make one of the first plastics
      - critical step in developing smokeless propellant
    - - 1884, Paul Vielle dissolved nitrocellulose in in alcohol and ether, formed it into thin sheets, and partially dried them into flexible sheets
      - plasticizer - residual alcohol and ether mixture that prevented sheets from shattering
      - sheets cut into small flakes burned inward from surface, reducing gas production; flake size changed rate of energy release
      - pros - gateway to modern propellants; still used for some purposes
      - cons - if alcohol and ether mix evaporated there was a decrease in rate of energy release; dry flakes could fracture into smaller sheets, increasing the energy release rate from the higher surface area
    - - 1887 - Alfred Nobel discovers dynamite, enabling nitroglycerin as an explosive
      - blend nitroglycerin with nitrocellulose
      - nitroglycerin acts as plasticizer and adds a lot of energy
      - nitrocellulose helped stabilize nitroglycerin and make it clean-burning in the absence of additional solvents
    - - mix acetone, nitrocellulose, nitroglycerin, and petroleum
      - evaporate solvent and stretch into long cords
- - - - lock: predictable ignition
      - stock: way to hold and control it (frame)
      - barrel: hollow tube to hold propellant and projectile
    - - ignition
      - pressure
      - chamber design function
      - chamber and cartridge dimensions
      - headspace considerations
  - - - curved metal rod pivoted around middle and held match at one end
      - slow - developed spring-powered lock system to speed it up; cock holds the match, trigger releases the spring-loaded cock; pull back on cock to load spring power; trigger releases cock to make match contact touchhole
      - touchhole moved to side, priming pan next to touchhole held priming powder - improved ignition
      - cons - match can go out, need to relight with flint and steel, useless when wet
    - - serrated steel wheel projected through lock plate
      - internally, wheel attached to spring that could be wound, storing energy
      - cock gripped flint piece; could be lowered onto wheel
      - trigger pull - release wheel, lower flint onto spinning wheel, produces sparks that fall into pan with small amount of powder
      - vent - connects pan to powder charge in barrel; sparks that ignite pan travel through vent to main charge
      - set trigger - reduce trigger pull when wheel tense; used today in precision target arms
      - cons - expensive (difficult to make), too complex for combat, residues can mess up intricate parts, spanner wrench needed for winding spring (loss leaves gun unusable)
    - - had offset powder pan of match/wheel locks, basic spring cock, flint holder instead of match
      - anvil - steel striking plate over side pan for flint to strike
      - cock falls against curved, hinged anvil, pushing it up and showering sparks into pan
    - - overcame priming pan problems - priming charge exposed, so it could be rendered useless by conditions or blown away; some had sliding pan covers (manual or automatic), but mechanisms could break
      - frizzen - combines priming pan cover and anvil; covers priming charge in pan; when cock falls, flint strikes anvil portion of frizzen, producing sparks; frizzen pushes up and opens so sparks fall into priming pan
      - pros - ready at moment's notice; relatively safe; don't need to remember to open pan cover; not waterproof, but protects against light rain and wind
    - - overcame issues with external pan - waterproofing, improved speed and ease of loading
      - temporarily close one end of barrel
      - pressure-sensitive mixtures; will not heat up enough to ignite propellant alone but will in combination
      - fulminating powders - developed by Forsyth, 1793; potassium chlorate with oxidizers; explodes when struck by hammer, flame passed through tube to main charge
      - Forsyth developed magazines - pivoted, held multiple pellets
      - variety of fulminate holders developed
    - - ~1814 - small, soft, iron cups; fulminate at bottom; later pewter and soft copper
      - 3 modifications from flintlock: drum, nipple, hammer
      - drum - enlarged hollow projection near vent hole and pan; usually integrated with barrel
      - nipple - removable, tapered tube; screwed into drum; held percussion cap; hit by hammer, high heat, and pressure; tapered so cap fits tightly and says in place
      - hammer - replaced flint clamp; directly contact rear face of nipple; improved sealing of percussion system
      - helped sealing of barrel - improved performance and waterproofing
  - - - rifling - spiraled grooves on barrel interior; causes bullet to spin, stabilizing it -> improved accuracy
      - distinction: muskets have smooth barrels, rifles have rifling
      - rifles slower and harder to load
    - - patch - tallow-soaked cloth or buckskin
      - wrap under-sized ball in patch to make up difference in diameter relative to barrel - easier to load with ramrod
      - patch helped keep most powder gas behind bullet
      - lead ball deformed to cylinder - cylinders require artificial stability, hence need for rifling spin
      - slugging - in-bore deformation of projectile due to pressure from firing
    - - smoothbore musket, loaded with cloth wad and bird shot, buckshot, or single large ball
      - bird shot - tiny lead pellets
      - buckshot - multiple larger pellets
      - rifling made pellets spin faster and disperse more, reducing the range - hence, shotguns need to be smoothbore
      - rifles and shotguns diverged, becoming distinct classes
  - - - evolved from percussion cap to self-contained cartridge
      - hammer had to be transferred to interior of arm where cartridge rested
      - arm had to be breech loaded - end opposite muzzle needs to accept cartridges (projectile, propellant, primer(
      - lock mechanism on arm had to contain cartridge under firing pressure
    - - basic mechanisms used in percussion shooters easily adapted to breech mechanisms
      - early locking mechanisms able to control modern cartridge
    - - need to make sure seal is secure enough so shooter does not get hit by gas and debris
      - 2 considerations - tolerance, sealing
      - tolerance - loose enough to let arm function through dirt and powder fouling
      - sealing - prevent gas leakage by slight expansion of soft brass cartridge (obturation) during firing
    - - frame - breech-loading firearms needed metal frame to support lock/latch system and be central point for attaching all parts
      - receiver - frame for repeating arms; added parts for receiving cartridges and moving them to barrel
      - latching methods needed to be firmer as firing power increased to keep breech from opening when fired; originally just needed pressure of shooter's hand
    - - barrel hinged to separate frame
      - frame holds firing mechanism and latch system
      - barrel tips down (or pivots to side) when latch opens, withdrawing locking bolt from barrel
      - used today in shotguns and some rifles
    - - frame slotted; breech block slides down for loading and up for firing
      - good, reliable; bulky, not convertible to be repeating firearms; support balanced above and below cartridge center line
    - - breech block below axis of bore; rotates to expose chamber to load
      - curved surface on block, matching surface on hammer; when hammer cocked, surfaces disengaged and block can be opened; when trigger is pulled, surfaces engage to hold breech closed
      - strongest actions are ones where support against thrust of cartridge is as strong above the center of the cartridge as below
      - easier to operate than falling block but not as strong; entire support is below center line of cartridge; not suitable for high-power of black powder
    - - early models locked for firing when handle closed against receiver; rotate handle to unlock it, pull back to expose chamber
      - bolt shape distributes thrust forces evenly - improved later
      - allowed for innovation of repeating bolt-action firearms
      - locking of bolt handle less effective with stronger cartridges; leaks
      - to fix, bolt handle became backup locking point instead
      - protruding lungs added to bolt body; rotated into slots when bolt action closed for firing; lung placement and number varied by model - best form was 2 large lungs just behind breech face
      - 2 rifles developed from French Chassepot model: Austrian Mannlicher and German Mauser
    - - split receiver bridge retained from Chassepot
      - bolt handle sits at ejection port when closed; must go through bridge to open, guiding bold handle and smoothing the action
      - split reduces ability to add extra features (ie. sights)
      - ammunition had to be packed in clips, which stay in rifle after loading and become part of feed system
    - - originally had split bridge with better safety mechanism; replaced with solid bridge in front of bolt handle by 1889
      - solid bridge gave support to stripper clips - allowed faster loading
      - by 1893, replaced external magazine with internal one; staggered cartridges to improve fit; durable
      - 1898 - best bolt-action rifle; 2 forward locking lungs, large safety lung at end of bolt body, projection behind bolt handle as safety lug; bolt body vented - channeled gas away from shooter; 3-position safety mechanism - safe to load and unload; feed mechanism controlled cartridge movement from magazine to cartridge; firing pin moved away from firing-pin release mechanism automatically; influenced most modern bolt-action sport rifles
  - - - repeating firearm - carries supply of ammunition, can move cartridges in and out of chamber
      - multishot wheel lock and flintlock - load charges (powder and projectile) one on top of another; front charge could ignite others accidentally
      - multibarrel arms - more shots in shorter time; bulky, heavy
      - percussion cap reduced bulk of firearm - more room for repeating mechanism that moves between barrel and firing mechanism
    - - cylinder chamber; charge holes parallel to barrel
      - lockwork important - chamber has to be aligned with barrel when firing or it can discharge lead shavings, which can injure shooter; misalignment reduces accuracy
      - Colt most successful - separate cylinder lock bolt from trigger
      - Colt hammer activation sequence: (1) start cocking hammer, bolt drops away and cylinder can rotate (2) before hammer finishes cocking, spring latch released from hammer and bore against turning cylinder (3) next latch hole in cylinder rolled around, latch springs into it, locking cylinder in firing position (4) cylinder locked before trigger pulled, ensuring alignment
      - Colt rate of fire slowed by manual cocking; Smith and Wesson created double-action revolver to increase rate - pulling trigger both cocked and fired revolver because cylinder-rotating mechanisms relocated from hammer to trigger
    - - bolt-actions easily modified to be repeating firearms; add long, tubular magazine under barrel; spring in magazine pushed cartridges up; tilting tray under bold took up cartridge when bolt handle pulled back
      - Early Winchester repeating firearms linked bolt lever to lifter block behind magazine; top of block knocked fired case from chamber when lever operated; as block rose further, new cartridge pushed up by magazine held in alignment with chamber and bolt pushed it forward
      - slide-action - similar internal parts to lever action, but connected to forearm of firearm; forearm movable; pulling support hand back unlocked and opened action for ejection and reloading
    - - tubular magazines loaded cartridges base to tip - could not hold ammunition with sharp bullets; recoil from one cartridge could hit cartridge behind it and bullet tip could act as firing pin - cartridge could discharge in magazine
      - box magazine - stack cartridges on top of each other; could be staggered side-to-side for more room; placed just in front of bolt face when action fully open
      - bottom of magazine spring-loaded
      - when action closed, bolt body holds cartridges in magazine
      - when bolt fully open and retracted, top cartridge pushed against raised ridges at top of magazine by spring, allowing bolt to push it into chamber
    - - recoil energy from first shot fired by trigger pull used to discharge successive cartridge, and so on
      - Hiram Maxim, 1884 - patent recoil-operated semiautomatic ; fully locked breech for high-power cartridges; long-recoil system
      - low-powered charges that reach peak pressure quickly - bolt does not need to lock to be safe; bolt mass and spring enough to hold bolt closed during firing
      - blowback - recoil-operated action; recoil and gas pressure push bolt open, remove spent cartridge, cock firing mechanism, and load fresh cartridge into chamber
      - high-powered charges - require locked breech to be safe; need more momentum to unlock bolt to use blowback cycle; extra momentum gained by letting some part of firearm move back with cartridge
      - short recoil - part moves back < 1/2 inch; long recoil - part movement nearly equal to cartridge length
    - - use gas from first cartridge to drive piston of repeating mechanism
      - most have ported barrels to bleed off gas; port size depends on position down barrel, pressure of cartridge, rate of pressure decrease as bullet moves down barrel
      - piston can be short or long stroke; gas enters chamber under barrel, one wall of which is the piston; piston moves rearward to impact end of rod attached to bold; impact unlocks action, recoil of cartridge pushes bolt open
      - blowback - firearms utilize breech pressure on head of cartridge case to activate mechanism; high fire rate
      - most submachine guns use blowback activation; firing sequence: (1) trigger holds cocked bolt back (2) trigger pull releases spring-loaded bolt to move forward (3) moving bolt strips top cartridge from magazine and moves it into chamber (4) cartridge fires as bolt closes, driving bolt back to repeat cycle
    - - need locking system to secure breech at very high pressure (65,000 psi)
      - slower rate of fire from locking and unlocking
      - can use spring-loaded box magazines, gravity feed magazines, or belts
- - - - original cannon projectiles were round stones
      - later, common metal used to cast cannon balls
      - for small arms, small stone or metal balls could be used; light weight resulted in low velocity and lower energy of impact - compensate for low velocity with larger mass
      - smelting used to make lead balls from common ore; inexpensive, easy to work with, low melting point; high density allowed long-range velocity
      - cons - needed to make larger balls to make them heavier, so larger gun barrels needed
    - - cylinder shape allowed heavier bullet in smaller barrel diameter
      - did not work with smooth bore firearm; tumble shortly after leaving barrel and lose accuracy and velocity - rifling necessary
      - attempts to use rifled firearms without needing patches - balls formed with high and low segments to fit rifling (difficult to load in fouled barrel), fit sabots to round balls (inconsistent, difficult to load, tipped often), undersized ball pounded with ramrod (stout ramrod required, dangerous)
      - solution - Col. Charles C. E. Minie; undersized, cylindrical bullet, cavity at base to ease loading into fouled bore; when fired, gas pressure expands skirt around base, causing base to flare out and increase bullet diameter to fit barrel; increased accuracy, better gas sealing, faster loading
    - - bullet jacket - any material surrounding bullet
      - cloth patches around balls earliest jacket; designed to engage rifling; other early jacket was paper to engage shallow rifling of single-shot rifles and target arms
      - smokeless propellants - higher velocity, pressure, temperature, and frictional force; could melt lead bullets to barrel and melt bearing surface; solution - metallic bullet jackets
      - metal jackets protected bullet, facilitated rifling, and allowed quick firing of cylindrical bullets
      - semijacketed bullets - controlled expansion; used in hunting
      - full metal jacket bullet - reliable feeding into chamber due to rigid tip; used in semiautomatic and automatic arms; military usage
  - - - functions of modern cartridges: contain components in one unit, take hit from firing pin, obturation (form gas seal)
      - designed to replace powder flask; original cartridge was paper tube filled with powder and a ball
      - early breechloader firearms had blad on top of breech lock that cut off end of tube when closing to open the propellant end - reduced misfires caused by excess paper blocking ignition flame
      - Burnside rifle - brass cartridge; hole in bottom took blast from percussion cap; powder ignited when seal burned through; did not expand well to seal bore
      - modern cartridge - expand under pressure to seal barrel; remain intact at high pressure; slightly smaller than chamber
    - - rimfire cartridge class - ball in copper case, hollow rim folded into base; fulminate inside hollow rim acted as sole propellant; firing pin strike ignited fulminate
      - pinfire cartridge case - fulminate pocket on sidewall of copper case; brass pin on other side of case; internal pin tip rested on fulminate; hammer hits side of case, pushing pin into fulminate and igniting it; required special gun chamber, expensive ammunition
      - needle-fire cartridge case - primer in bullet base, long pin pierced paper case to ignite primer; poor sealing
      - 1854 - Volcanic cartridge system, Robbins and Lawrence; Minie ball, base filled with propellant; paper disc separated fulminate at back; underpowered, poor seal; Volcanic repeating rifle could hold lot of ammunition
    - - put into use around Civil War - simple to use and make
      - percussion breechloaders modified to use cartridges (usually rimfire)
      - early rimfire cartridges misfired easily - primer glued to rim; if jostled, fulminate could fall out of rim cavity
      - thin case - limited power; thickening rim caused misfire issues
    - - centerfire - pellet at center of cartridge base; firing pins had to be moved to hit center rather than rim
      - internally primed system - separate metal structure held priming pellet; priming pellet pushed into case's base and crimped in place before propellant charging; ie. Benet system and Martin bar anvil system
      - thin, flexible case needed for firing pin impact to ignite fulminate; solution: stronger case with thin metal over primer pellet by separating case from primer
    - - pocket placed on rear of casing to hold primer; anvil surface that struck fulminate when firing pin hit primer
      - small holes connecting primer to main charge
      - fold stressed metal - could become brittle over time and fail
    - - case forged instead of folded - stronger, primer pocket could extend into main charge space; stress at center reduced
      - used through 1960s in North America in low-pressure revolvers
      - solid-head case - needed less space with smokeless propellant - used extra room to strengthen case
    - - most variation in cases is in primer pocket
      - Boxer priming - anvil in primer as separate part; pocket has one large hole at centerline; can reuse the casing - remove used primer with small punch tool and insert new one; used in America
      - Berdan priming - anvil integral part of case; 1-3 small flash holes positioned around anvil; used by most of the rest of the world
      - brass common in Western Europe and American sporting firearms; mild steel also used in some places where copper not very common
      - modern shotgun casings have paper or flexible plastic body, plastic base was around primer, metal base for extractor grip and primer support
    - - no universal system in North America - commercially driven
      - universal system in Europe controlled by government
    - - basic shape connected to firearms development - originally straight walled (best for black powder); rims at rear prevented firing from blowing casing into barrel and provided grip for extractor
      - protruding rim removed for magazines - new case had to provide support for positioning, resist blow from firing pin, and have some way for extractor to grip it
      - support - some used case mouth to support cartridge, some cartridges bottlnecked, some had belted case
      - grip - developed rimless case; rim still present, but not wider than rest of case; used groove cut into case instead
  - - - primer - burn or explode to ignite main charge when struck
      - functions - provide initial spark, provide preignition pressure, form gas seal
      - mercury fulminate most common primer for long time
      - mercuric residue made brass cartridges brittle; okay for first firing, but couldn't be reused
      - potassium chlorate replaced fulminate for brass casings
      - 1898 - mercury fulminate abandoned by U.S. military with introduction of smokeless powder
    - - 1920s - lead styphnate used; did not cause corrosion; mix of lead styphnate, antimony sulfide fuel, and barium nitrate oxidizer
      - other components of styphnate primer: sensitzer, aluminum, binder, dye
      - sensitizer - made blend more sensitive to shock; tetracene popular
      - powdered aluminum - added fuel; incandescent particles added to propellant
      - organic binder - hold primer together when dry
      - dye - easier to see primer during manufacturing
      - Boxer primer minimum components: metal cup, primer, anvil; many have paper barrier between primer and anvil (foil paper)
      - shotshell primers - battery cup added to oppose pressure and support anvil; paper or thin plastic barrier over flash hole