First up I'm going to echo what everyone else has said about Jane's Guns - "every firearm in use today."
Off the top of my head it's got no HKMP5 (but does list the MP5K), only lists one Thompson submachine-gun (variants have important differences). The Sten MK3 is no longer present. The revolvers section is full of ancient Beaumont - Adams revolvers and old pre-war Webleys, but it does not list the WW1 Webley MK VI Service Revolver and the Colt Peacemaker which are surely more common than these other marques. Strangely, the Webley MKVI was featured in older editions of Jane's Guns. There are no Mateba Autorevolvers. There is no Enfield SA80K, though it does list the L86 DMR (on the cover) and the L85A2 (SA80). The Colt Commando shortened M4 Carbine is removed. Some bolt action rifles are missing. There are many other omissions.
Conversely, the section on Machine Guns is as vast and exhaustive as ever, even pre-WW1 designs are featured. Surely these are encountered more rarely than a Colt Peacemaker or an HKMP5. There doesn't seem to be much consistency.
Also, some detail is incorrect. This would be understandable if it was a cheap, toilet-dwelling, time-passing throwaway reference guide, but it's an expensive identification book and you'd expect more quality for that kind of money. And if not quality, quantity.
On the plus side, it is well written, there are some darkly amusing passages, especially in the Machine Guns category and despite the omissions it still lists a huge amount of firearms and accurately explains (in the main) how to identify, unload and make safe the vast majority of guns in the world. Until someone gets fed up and makes another better guide, there is no better reference book for small arms in the world. Unfortunately.
Superb book a must for anyone with an interest in firearms from the enthusiast right up to the professional military and policing levels. This book has excellent pictures and detailed technical specifications on all the firearms featured. Highly recommended.
This book is an excellent guide for those of you who are into the world of guns. Contrary to 'major tom' the mp-5 base model is included in the 2005 edition. however, despite my high praises for this book it would be nice if the weopons in it were kept more up to date i.e. more recent weapons, but the old guns should stay in! There are various (now) common use assault rifles which have not even been mentioned in the text, as you have to check each description for the sub models and variants. Some of the weapons included for instance, the israeli magal, barely saw service since there were problems which forced it to be withdrawn from service, so blatantly should be omitted. However, this book is a worthwhile buy, especially at the price it is sold on amazon (£11 as opposed to £20)!