Gun development and design in Europe reached its "classic" form in the 1480s – longer, lighter, more efficient, and more accurate compared to its predecessors only three decades prior. The design persisted, and cannons of the 1480s show little difference and surprising similarity with cannons three centuries later in the 1750s. This 300-year period during which the classic cannon dominated gives it its moniker.
The early classical European guns are exemplified by two cannons from 1488 now preserved in a plaza in Neuchâtel, Switzerland. The Neuchâtel guns are 224 centimeters long, with a bore of 6.2 centimeters and the other is slightly longer, 252 centimeters, with the same bore size. They are differentiated from older firearms by an assortment of improvements. Their longer length-to-bore ratio imparts more energy into the shot, enabling the projectile to shoot further. Not only longer, they were also lighter as the barrel walls were made thinner to allow for faster dissipation of heat. They also no longer needed the help of a wooden plug to load since they offered a tighter fit between projectile and barrel, further increasing the accuracy of gunpowder warfare – and were deadlier due to developments such as gunpowder corning and iron shot. When these guns reached China in the 1510s, the Chinese were highly impressed by them, primarily for their longer and thinner barrels.
The two primary theories for the appearance of the classic gun involve the development of gunpowder corning and a new method for casting guns.
The corning hypothesis stipulates that the longer barrels came about as a reaction to the development of corned gunpowder. Not only did "corned" powder keep better, because of its reduced surface area, but gunners also found that it was more powerful and easier to load into guns. Prior to corning, gunpowder would also frequently demix into its constitutive components and was therefore unreliable. The faster gunpowder reaction was suitable for smaller guns, since large ones had a tendency to crack, and the more controlled reaction allowed large guns to have longer, thinner walls. However, the corning hypothesis has been argued against on two grounds: One, the powder makers were probably more worried about spoilage than the effect of corned gunpowder on guns; and two, corning as a practice had existed in China (for explosives) since the 1370s.
The second theory is that the key to developing the classic gun may have been a new method of gun casting, muzzle side up. Smith observes: "The surviving pieces of ordnance from earlier in the 15th century are big pieces with large bore sizes. They do not look like the long thin gun.… Essentially they are parallel-sided tubes with flat ends. The explanation is, probably, that they were cast muzzle down in the traditional bell-founding method whereas the long thin guns were cast muzzle up.… Perhaps this marks the real revolution in artillery. Once the technique of casting muzzle up with the attendant advantages, and it is not clear what those are at present, had been mastered by cannon founders, the way was open for the development of the classic form of artillery." However, Smith himself states that it is not clear what advantages this technique would have conferred, despite its widespread adoption.