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What is the difference between a switchblade and a spring assisted opening knife?

Switchblade knives were invented in the early part of the 20th century. During the 1950's the switchblade got a bad reputation as it was identified with gangs which were popularized by such movies as "On the Waterfront", etc. As a result in the late 1950's most states passed laws outlawing the possession of switchblade knives. A Federal statute was passed to make it unlawful to ship switchblades across state lines, unless being shipped to a law enforcement or military agency. Here we will explain the difference between illegal switchblade knives, and legal spring assisted opening knives.

All switchblades have some characteristics in common. They have a spring which exerts constant pressure on the blade. The knife is held in the closed position by the mechanism of the knife. This mechanism is released by depressing the button (which all switchblades have), allowing the stored energy the spring is exerting on the blade to propel the blade from the handle and open the knife. It is important to remember that the natural position of the switchblade knife is OPEN, it is held closed only by the locking mechanism.

On the other hand, the natural position of the spring assisted opening knife is CLOSED. There is no pressure being exerted upon the blade, and there is no button to push. Spring assisted knives employ the following opening methods:

1) A "Flipper" or lever which is located on the back spine of the knife. This flipper is actually an integral part of the blade which protrudes from the back spine of the knife when it is in the closed position. This is the most common opening mechanism of spring assisted knives.

2). A thumb stud, the same as is found on most all tactical folding knives.

In either case, either flicking the "flipper" or pushing out the thumb stud begins opening the blade, at which point the assisted opening mechanism takes over and finishes opening the blade. Performance wise, there is very little (if any) difference in the opening speed of a switchblade and a spring assisted knife. However, the differences in the way they are made make the spring assisted knives legal in all 50 U.S. states (They are not legal in the 5 boroughs of New York City, but this is because all locking blade knives have been held to be illegal in NYC, not just the spring assisted ones).

We hope this information has been helpful. If you have any other questions about this or any other knife topics, please send us an email and we will be happy to answer them for you to the best of our ability.