Re: What is a reamer?
In this case, a reamer is a fluted cutter that is used for chambering rifle barrels. The throat and lead is ground onto the end of the reamer and the entire chamber, throat and lead are cut at the same time. The lead is 99.9% of the time 1 1/2 degrees, the throat is based on your bullet and seating depth. Theres also a removable piolet that attaches to the end of the reamer to help it follow the bore. There are other types of reamers (non-chambering) that are used when a perfectly round holes are needed in machinging process's and are not only for gunsmiths.