The need to have a basic knowledge of locks, how to open or pick them came up in a thread yesterday… Here is a pretty good book on the subject. It covers all the basics, has excellent illustrations and uses easy to follow descriptions. https://www.homesteadingforum.org/threads/lock-picking.7330/#post-199233 Visual Guide to Lock Picking 3rd Edition By McCloud & Santos Copyright 2006 At the end of the day you can easily open 75% of the residential door locks and 95% of the pad locks used in the US with only 2 tools… A rake and a torque wrench. What makes some residential door locks difficult isn’t the design, it’s quality of the parts. The basic design of these locks hasn’t changed in 50 years. The pins of quality door locks like Schlage have really tight tolerances. The pins in cheaper door locks are down right sloppy making them easy pickins’ (pardon the pun). The number of pins in a lock whether cheap or well-made increase the difficulty. Most use 4 or less, good locks use 4+. Anyway, this book will give basic understanding of locks to preppers and the tools used to open them.