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.
The stomach has three main parts. The top is called the fundus. The middle is called the body of the stomach. The bottom is called the antrum or pylorus. There is a valve called a sphincter at each end of the stomach. The valve between the oesophagus and the top of the stomach is called the cardiac sphincter.