[Snap Cap]

Bruce, I have attempted to enter some information on the meaning of killing circles circa 1910 for three nights in a row and have been frustrated by the timing out of this web site's sign in feature, i.e. after typing in a couple of paragraphs and hitting the reply button, i am directed to sign in again and after doing such, I am directed to back key to enter a reply, and proceed to lose all the reply's contents. Therefore, I now surrender and instead of giving a detailed answer siting sources, I will just leave this terse answer:

Bruce, this term does make for some interesting reading in the shooting literature. In The Gun and Its Development 1910 edition Greener says: " The term "Killing Circles" is used to designate the extent of the spread of the pellets in a lateral direction, so long as the "pattern" is not too wide to allow of the escape of the game." Pages 369-385 go on to illustrate several different 30 inch patterns and give the killing circle size for each. The size bird illustrated is a Pigeon. HTH.