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Manufacturing tolerances for both ca
It should perhaps be noted that even if shot and bore were a perfect fit initially, they wouldn't necessarily stay that way. The shot would rust; the bore would be fouled. Both were subject to expansion when heated, which I would think would especially be a problem for the gun if it had been fired repeatedly. Douglas (74) suggested that at white heat 24-pound shot expanded by 1/70th diameter, and smaller shots by less.
Guns may also be classified according to their construction, as muzzle or breech loading, and as smoothbore or rifled.
Muzzle versus Breech Loading
The ca
A breechloader could have either an integral chamber, into which the powder and shot were placed directly, or a removable chamber (Buchanan 251ff); this would be loaded with the powder and shot and then the chamber placed in the breech. The removable chamber looked somewhat like a beer mug.
The proponents of muzzle loading and breech loading have engaged in a half-mille
The first naval ca
Muzzle loaders usually were brought inboard for loading. According to Martin and Parker (193), this was done manually; "the much more efficient process of allowing a gun's own recoil to bring it inboard under the restraint of a breeching rope was not developed until well into the seventeenth century." Smith, Seaman's Grammar(1627) says, "britchings are the ropes by which you lash your Ordnance fast to the Ships side"; in the light of Martin's comment, these lashings were too tight for recoil-aided loading.
The longer the barrel, the less convenient it was to load it from the muzzle end, and high-caliber guns tended to have long barrels. With black powder, there wasn't much advantage to making barrels longer than 10 feet, because the powder burns quickly, but with cordite the lengthening of the gun barrels permitted an increase in muzzle velocity. (Sweet 171).
On the Mary Rose, the gun crews were so cramped that it's been suggested that they engaged in outboard loading; the gu
While short-barreled carronades were easy to load, they had other problems; the flash could set fire to the rigging, and the vent fire could do the same to the hammocks. (Douglas 103).
For anysmoothbore muzzle loader, the shot had to fit loosely in the bore, so it could be rammed down. But when fired, gas could escape around the shot and out the muzzle, and it was also difficult to keep the projectile centered as it moved down bore.
Late in the history of muzzle loading artillery, the gas escape problem was reduced by use of a gas check, a thin disk that filled the cross-section of the bore. The first gas check was a papier machedisk inserted between the cartridge and the base of the shot, but by 1878 a copper disk was attached to the base of the projectile. (Ruffert). The centering problem theoretically could have been addressed with a sabot (see part 3), but that wasn't normally done.
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The most obvious advantage of the breech loading system was that the gun could be reloaded from inboard while run out, which potentially increased the rate of fire.
The most enduring design problem with breechloaders, which had a door rather than solid metal at the breech end, was preventing gas loss at the breech. The more powerful the gun, and the greater the strength of the powder, the greater the pressure that this mechanism had to withstand.
In Elizabethan breechloaders, the removable chamber was wedged into the breech. Lucar (1588) warns that the gu
According to EB11/Ordnance, the first successful breech mechanism was that invented by Armstrong (1854). The vent piece (a vertically sliding block) was secured by pressure from a hollow screw. To load, this was loosened, the vent piece removed, and the projectile and charge inserted through the hollow. The vent piece was then replaced and the screw tightened. On the chamber side the vent piece had a coned copper ring that fitted into a coned seating.
Unfortunately, the success was limited. "During the bombardment of Kagoshima in 1863 there were 28 accidents in the 365 rounds fired from 21 guns. On a number of occasions the vent pieces were blown from the guns. The guns were also inaccurate." (Brassington).
Moreover, the rise of the ironclads demanded an increase in punch, and the imperfect seals of the mid-nineteenth-century breechloaders frustrated this. The British navy conducted comparative trials and in 1865 it decided to switch to rifled muzzleloaders! (Hogg 16).
This turnabout didn't last long. In 1879, one of the guns of the HMS Thunderermisfired; the misfire was undetected and the gun was reloaded, making it inadvertently double-shotted. When the gun fired again, it exploded, killing everyone in the turret. This accident couldn't have happened with a breechloader-the gun crew would have seen the unexploded charge when it opened the breech-and the British navy reluctantly abandoned muzzle-loading for good (Batchelor 11). At least for new construction; there were still battleships with big muzzle loaders in active service in 1894 (Clowes 47).
This accident provided the impetus for change, but there were other considerations at work. A new powder that could achieve a higher muzzle velocity had been developed. But if it was used in a muzzle loader, the shell zipped out before the charge was exhausted. In other words, the barrels weren't long enough. But if the barrels were lengthened, then recoil wasn't sufficient to bring the muzzle inside the turret for loading. This was actually done on HMS Inflexible(1876) (Watts 56); the muzzle was lowered to an armored loading hatch and the shell inserted by a hydraulic rammer.