Reviving an old thread here.

Dust Tactics has inspired me to read up on various WW2 weapons.

I'm interested mostly in German small arms, tanks, artillery, aircraft, etc.  I don't mind buying different books for different topics.

What I'm most interested in, I suppose, is the development history.  Stuff like how encounters with heavy Russian tanks affected the development of the Tiger tank or how the Sturmgewehr 44 was developed to replace both submachine guns and rifles. 

I'd also like to read about operational history.  Stuff like how the Tiger's treads ended up being problematic from a reliability standpoint.  I find that kind of thing fascinating.

I already have Cormack and Smedley's "German Small Arms of World War 2" which has lots of photos, but not enough text.

I find that most WWII books on small arms and artillery are picture heavy and not a whole lot of text or scholarly research.  To get a deeper understanding of their use and why, you may need to check out "tactics" books like the many Stephen Bull books from the Osprey series (of which there many titles are pretty thin and not cheap) or his  SECOND WORLD WAR INFANTRY TACTICS: The European Theatre from Pen and Sword, or maybe Panzer Tactics: German Small-Unit Armor Tactics in World War II by Wolfgang Schneider or the two Panzertruppen books by Thomas Jentz for armor tactics and battle reports.