Dear Evil Engineer,

I manage a fast-growing agency which provides innovative sniping solutions to clients across a range of sectors. I like to work closely with mercenary snipers to ensure that they have access to the best tools and training available. Recently, I have been considering alternatives to conventional lead bullets. I’m fascinated by the idea of ice bullets which melt after use, leaving no trace behind them. Is such a thing possible?

Yours,
A stealthy villain

Dear villain,
Thank you for writing in. Despite an intriguing concept, I’m sorry to say that bullets made of ice may be some of the least effective tools imaginable. That is not to say that ice projectiles are entirely hopeless. Permit me to explain.

A bullet made of ice is highly unlikely to reach a sniper’s target, being prone to melting before so much as leaving the barrel. Firearms are quite inefficient, with only a small fraction of the initial chemical energy being converted into...