What are the characteristics of Carlson in Of Mice and Men and how can I study literature more efficiently?

The fact that Carlson owns a German Luger seems intended to show that he is a World War I veteran who brought the handgun back from Europe as a souvenir. He keeps it loaded, as we see after he shoots Candy's dog. Those were tough times and tough men traveling on freight trains, living in hobo jungles, and picking up odd jobs whenever and wherever they could. Carlson keeps the gun for protection. If he was in his twenties when he served in World War I, then he would be close to forty by 1937. He sees no future for himself but hard work, low pay, and old age. He exists mainly because Steinbeck wanted to show a cross-section of the types of men who did the unskilled farm labor in the 1930s. Some were young, some were middle aged like Carlson and Slim, and some were old and used up like Candy and Crooks.

Carlson is bothered by the bad smell of Candy's old dog because it reminds him of all the bunkhouses he has had to live in for the past twenty years. It is the bad smell of his own life. He is aloof and surly. He is fed up with life and with the kind of men he has to live with. His life had a purpose when he was in the war, and he was young enough to have illusions about the future. But Steinbeck uses the incident of killing the dog for a more important reason. He had to establish that there was a gun available and that George would know how to use it when the time came to kill Lennie. When the Luger is first shown, it is what in Hollywood is called a "plant." If a weapon is going to be used at some point in a film, that weapon is customarily shown earlier to establish where and what it is. George saw where Carlson kept his German pistol and how the mechanism worked. It had to be a distinctive-looking gun. Steinbeck intended to turn the novella into a stage play immediately, and the audience would need to recognize the gun as Carlson's when George pulled it out of his pocket. They would realize that George had stolen it with the intention of killing Lennie at the place where he knew Lennie would be hiding. A German Luger is a very distinctive-looking automatic pistol. It had to be a pistol, of course, because George could hardly produce a rifle, and if he tried to strangle Lennie or even stab him to death, he might end up getting killed himself by the bigger, stronger man.

World War II changed everything for white male farm workers. The U.S. government started spending billions on ships, planes, guns, munitions, supplies, etc., even before America was drawn into the conflict. The white males were able to get good defense jobs in or near cities and never went back to the California farms again. Farm labor was taken over by men and women from Mexico, who were pretty much excluded from defense work because of the language barrier.