Le May was actually given a demonstration on how the bullet coins were made.
My co-author, Vasilijs Mihailovs, personally conducted assays on a wide range of bullet coins and found their silver content to average out at about 96 per cent. I arranged for follow up assays at the Gem and Jewellery Institute of Thailand and their results confirm this.
Ronachai Krisadaolarn
author, ‘Siamese Coins from Funan to the Fifth Reign’
published by Riverbooks