carbine

Question
what exactly is a carbine  

Answer
John,

That's a very good question.  It's kind of like asking "What's a chair?"  In other words, can it have no legs and still be a chair?  Does it have to have a back to be a chair?  Can it be hard or must it be padded?

Somehow, although there may be a number of variations, we recognize the think as a chair, whatever its configuration.

Generally, a carbine is a short barreled rifle.  How short?  That's hard to say.  Shorter than what you're used to looking at as a rifle.  Usually, the name carbine is given to a rifle that is shorter than the one in service or vogue at the time.

So, for example, compared to Nagant bolt action rifles (Russian), SKS and AK47 are carbines.  Relative to the M1 Garand was the M1 Carbine.

The current issue M4 (usually a 14" barrel) is said to be the carbine version of the M16 (20" barrel).  An civilian AR15 with a 16" barrel (legal limit)is also often called a carbine.

Often times, carbines have pistol or intermediate cartridges, although it would not be impossible to find a carbine chambered in a bonafide rifle cartridge (such as .308 or .30-06).

When you hear "carbine" think "short rifle."  How short?  Shorter than what person who called it a carbine is used to seeing.

Hope this helps.