If so, what is the cultural explanation ? Their "culture" not there mode of production did it ? That sounds more insulting than that they got used to using force to herd animals and when they got to America it slopped over a bit into their relationships with Indigenous people and Africans who were slaves and considered less than human anyway in the culture of America because of the importance of the capitalist slave mode of production in the colonies. This would be a second way in which the culture in America was determined by the structure of the mode of production; infrastructure determining superstructure. This would be more likely because a new superstructure or culture was being created in America, relative to Europe, at this time. It wasn't the "frontier" or con_frontation_ with the physical an geographical environment that did it ( pace Frederick Jackson Turner; environmental determinism). It was the new organization of production, combining the old organzation with the new, the new division of labor and relationship of classes in America in the frontier that did it.... did what ? Made Southerners a bit mean in suppressing Indigneous peoples and Africans to the extreme.
Come to think of it, a better explanation of Americans' gun fetish culture is that guns were absolutely critical and necessary to conquer the Indigenous People and suppress African slaves. The treatment of the Africans was somewhat like that of beasts of burden,oxen or cattle/chattel. They used whips as well as guns. It was chattel slavery.
A weakness of fancy marxism is that it sometimes fails to realize that relatively vulgar materialist explanations are not always wrong.