I have `Brassey's Land Warfare into the 21st century - Guided Weapons (3rd edition)', marked inside as `Brassey's NEW (my emphasis) Battlefield Weapons Systems and Technology Series into the 21st century, Volume 5'. On another page it says that this book is a volume of Series 3. It was published in 1998. My copy is a hardback, ISBN 1 85753 152 3.
Other volumes in Series 3 that are listed as companion titles are Vol 1 - Military ballistics: A basic manual; Vol 2 - Cannons; Vol 3 -Guns, mortars & rockets, revised; Vol 4 - Surveillance & target acquisition systems (2nd edition); Vol 6 - Small arms & machine guns; Vol 7 - Explosives, propellants & pyrotechnics (2nd edition).
I also have `Brassey's NEW (my emphasis) Battlefield Weapons Systems and Technology Series, Volume 4 - Ammunition for the land battle' published in 1991, in paperback, ISBN 0 08 035907 1. This is a volume in Series 2.
Some of the titles are the same between the two series but their volume numbers are different. Which series is your Volume 3 part of?