I don't know... every country with its rings... your first suggestion can be the true one, becouse I don't think that a country like Germany is saving money with smaller rings, and the rings aren't heavy, even for a pigeon...
This is an homer from Romania. It is 23 years old, and, a few years ago the fancier who had that pigeon died... The pigeon lived only with water, corn and grain. There is the site:
http://www.porumbei.ro/mosneagul-40367-1986-rsr/