Tracer Question

What is the specific function of the metalic sealing disk used in some tracer bullets such as the Spotter/Tracer BAT projectile (so nicely sectioned in Dec. cartridge of the month)?

One would think the disk would cause reliable ignition problems for the tracer composition. I can understand keeping the propellant powder and brass case interior separate from the tracer but where does the disk go when the thing lights up?


It is a very thin foil and it melts away. The moisture barrier it provides ensures reliable ignition of the tracer.



Thanks for the response. The interior of a round being fired does make for a rather warm environment…