It only takes a few minutes to produce a barrel in this way but the machinery is very expensive, which is why only larger manufacturers use this method. Button-rifled barrels are also made by drilling, grinding and polishing. The rifling pattern is then pressed into the barrel with a tool called a button. Afterwards the barrel is polished with a lead rod and grinding paste.
An antrum is a cavity or chamber, such as the antrum of the lower  part of the stomach. Erosion means that the lining is thinning,  resulting in inflammation and irritation.â¦ Erythema describes a  reddening of tissue due to irritation or injury. (MORE) 25 people found this useful.
Ruminant stomach. The ruminant stomach is a multi-chambered organ found in ruminants (see picture at right). It is usually composed of four separate chambers and allows digestion of large quantities of plant matter that would be relatively indigestible for most other types of mammals, in particular grass and the leaves.