"Are you sure it's coated on the base? Anyways I've seen some photos of WW2 era cannon shells and some of them look like they have something "painted" onto them."
Perhaps the paint was just for identification, or perhaps you are mistaken. Nonetheless, I've found a page
here that goes into some detail about an experiment with "external tracer" from 1975. It doesn't seem to have been a successful experiment:
"As a preliminary study of the utility of one concept of 'external tracer', five types of chemically coated ball ammunition (which, when fired, left visible vapor trails to mark projectile trajectory) were compared with 7.62mm M62 tracer, 5.56mm M196 tracer and 7.62mm ball ammunition on two measures of observation. Twenty infantrymen reported after each of 80 single rounds whether tracer was detected and which of three targets 400 meters downrange was engaged. Standard tracers (M62 and M196) were associated with substantially more accuracy in ammunition target identification than external tracers. Only when observers in daylight were located directly behind the weapon firing were they able to detect external tracer with an accuracy approaching that of standard tracer."
Sadly there are no pictures. The tracer is said to leave "vapor trails", which is American for "vapour trails". I imagine there would have been several practical difficulties related to the handling of these rounds. I can picture the soldiers licking them to get high. There is a similar patent from 2006
here, although the concept involves flourescent chemicals. I quote:
"the light-emitting chemical comprises a mixture of a first chemlucent chemical and a second chemlucent chemical, wherein the first chemlucent chemical is contained in a plurality of glass vials which are
restrained by a spider and emplaced in a bag."
There is mention
here of anti-balloon bullets from WW1:
"Fighters were ordered to attack balloons as soon as, and wherever, they appeared. At the time highly flammable hydrogen gas was used to inflate the balloons, so they were very vulnerable to tracer bullets coated with flammable phosphorus."
Assuming that this article is correct, and that the bullets really were coated with phosphorous, I imagine the bullets would have been extremely hard to handle and work with. It leads me to this short page about a "
Pomeroy bullet ", which amuses me because I share that man's surname.
Plastic BB gun tracers, as far as I know, are made of a flourescent material that is lit by a strobe light as the bullets leave the barrel; perhaps with modern polymers this concept could be expanded to small arms ammunition, although the polymer would have to be biodegradable.
Living as I do in the UK this is all theory. I own an air rifle but I have never heard of air rifle tracer pellets.
This bulletin board should have a button people can press that lights up a light in Tony Williams' mansion so that he can dive in an write five hundred interesting words on a given topic.
