I read a book in the early 80's (sometime between 81 and 83) that I have been trying to remember the title of for a long time. I got the book from my high school librarian as a reading suggestion, so it may have been a young adult book, but I don't know. 

The only think I remember about the story is one of the weapons that the "good guys" wore. 

The weapon was a hand gun type of weapon that they wore in a holster that was on the forearm of their gun hand. The weapon was somehow connected to the nerves in their wrist so that when they tensed their hand or arm in a certain way the gun jumped into their hand.