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.
Alpha-fetoprotein (AFP) is a fetal protein that is initially produced in the fetal yolk sac and liver. A small amount also is produced by the gastrointestinal tract. By the end of the first trimester, nearly all of the AFP is produced by the fetal liver. The concentration of AFP peaks in fetal serum between 10 to 13 weeks. Fetal AFP diffuses across the placental barrier into the maternal circulation. A small amount also is transported from the amniotic cavity.