lead shot sizes

Question
We know how shotgun gauges are determined (number of lead balls poer pound).  But how were the diameters of lead shot decided.  Who decided what the diameter of a #7 shot pellet, or a BB or T pellet should be?

Answer
Hi Greg,

I wish there was one hard fast answer to your question that gave an exact answer as to shot size. Unfortunately it not a world wide exact science or standard.

There are at least 24 different charts and systems of shot sizes in use by different countries. In actuality, shot size is more of relative term than a true measurement.

In the U.S. the shot size is roughly determined as follows. Shot screening is used to sort the shot.  The size of the mesh in the screening is the standard by which the shot size is rated. The finer the mesh the smaller the shot passed. Sizes run in increments of .01"

The diameter of the shot in hundredths of an inch is determined by substacting the shot size from the number 17. IE. Shot size #8 is .09" #6 is .11" and so on.

I hope this helps. Thank you for your question.

Sid Lark