Guns are useless without bullets. An Arms Trade Treaty (ATT) that does not control ammunition will not achieve its purposes. Several countries, including the USA, China, Egypt and Syria, are arguing that ammunition should be excluded from the ATT. Some of these countries say the sheer volume of trade makes it too difficult to monitor. This would be a colossal mistake. There are now several reasonably simple and effective ways to track ammunition transfers. Inclusion in the ATT would significantly strengthen these mechanisms and the resolve to implement them. Failure would undermine what best practice already exists.