Later lists of ordnance show pieces additional to those shown in Table 1, mostly variations of the basic, some of which no doubt resulted from the method of production outlined above. For example, a bastard piece was one the dimensions of which differed in some way from the pattern. Also, as guns were expected to last for decades there appear old, eldest, ordinary, extraordinary, as well as foreign, ie imported, types. Broadly divided into siege and field, some idea may be gained of their respective employment by a study of Table 2. Both tables refer to English ordnance but types produced in European countries were similar.

In 1665 in England (later in Europe), the old names, eg cannon, culverin, etc, began to be dropped and the guns designated by the weight of shot fired (Table 3). Here we find the first application of a modern basic principle, ie that the projectile is the weapon of the artillery, the gun merely the means of putting it on to the target. The arbitrary progression of calibres by one half or one quarter inch has disappeared. In its place are guns firing projectiles selected for their individual effectiveness, eg the 24-pr fired from a gun of 5.824-inch calibre was found to have the best projectile for all-round siege work.

Note that windage has been changed from one quarter inch for all types to one twentieth the shot diameter - which improved the performance of the smaller guns but not those of 24-pr or larger. ''Rules of thumb'' had still not been entirely discarded. Note also that heavy ''brass'' guns (which were in fact bronze) became obsolescent c1800 because they could not stand high rates of fire as well as those of iron. The lighter field pieces only were retained.