As the "Mary Rose" was built and served during a period of rapid development of heavy artillery, her armament was a mix of old designs and innovations. The heavy armament was a mix of older-type wrought iron and cast bronze guns, which differed considerably in size, range and design. The large iron guns were made up of staves or bars welded into cylinders and then reinforced by shrinking iron hoops and breech loaded and equipped with simpler gun-carriages made from hollowed-out elm logs with only one pair of wheels, or without wheels entirely. The bronze guns were cast in one piece and rested on four-wheel carriages which were essentially the same as those used until the 19th century. The breech-loaders were cheaper to produce and both easier and faster to reload, but could take less powerful charges than cast bronze guns. Generally, the bronze guns used cast iron shot and were more suited to penetrate hull sides while the iron guns used stone shot that would shatter on impact and leave large, jagged holes, but both could also fire a variety of ammunition intended to destroy rigging and light structure or injure enemy personnel.