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.
pyloric antrum, antrum pyloricum. the lumen of the pyloric part of the stomach; the pump of the stomach, regulating the propulsion of food through the pylorus into the duodenum.