Whatever kind of carbine you select, its absolutely required capability is speed in hitting a close target. The short range snap shot is the life saving shot, the one you must not miss or delay.
The carbine is the most versatile of fighting firearms. A well designed example can serve most functions of pistol and rifle. It will serve better for close defense than any pistol and reach out to much longer distances.
The M1 carbine, introduced in the WWII era, was a great little carbine in many ways, delightfully handy and light, but it had some problems. Its cartridge was no powerhouse and the long distance accuracy of many GI carbines was hit and miss. (Unless the little gun is set up just right it will throw fliers out of its groups.) The M1 Carbine taught the shooting world some important lessons. Ergonomic form and light weight count for a lot, but so does a cartridge that finishes the fight.
|Left to right, first row: Eisenhower, Churchill, Bradley. M1 Carbines.|
The current M4 carbine is, of course, a shortened M16, with some variations and adaptations to make the mechanism work in an abbreviated package. Its ergos are pretty good and it is of a handy length. Its accuracy is generally very good. Complaints about the M4 are mainly that it fires the 5.56, and does so at a lesser velocity than the M16. If the M16 and its cartridge are marginal at long range the M4 is more so. Neither weapon is ideal for long range encounters in wide open country, but that kind of fighting is unusual, historically speaking.
|Marine shoots M4|
The Tavor rifle counts as a carbine because it is very short, a result of its bullpup construction with the action to the rear. The person used to the balance and form of a conventional carbine will need to get used to the Tavor, but it appears to be an excellent performer, accurate and reliable.
Turning to older technology, the lever action .30-30 is fantastically successful throughout the Americas, as a general purpose weapon for outdoorsmen. It also serves some people as a defense and emergency preparedness arm. They already have a deer rifle and suppose that is sufficient; they may be right at that. The lever carbine is convenient in its operation, well balanced and comes quickly onto the target for the snap shot. It points naturally for most people, contributing to their confidence with it. I count five manufacturers currently offering versions of this historic weapon and I cannot count all the people carrying these things afield for game or for protection.
|Unknown actor with lever carbine|
Mossberg has startled traditionalists with its 464 SPX, a .30-30 tricked out with an adjustable stock resembling the M4's, a rail mount fore end and a threaded muzzle. I kind of like it. If these mods make sense on a modern rifle, they make equal sense on an older design. If it all seems a bit much, though, Mossberg will of course be happy to supply you with a traditional looking .30-30.
Whatever kind of carbine you select, its absolutely required capability is speed in hitting a close target. The short range snap shot is the life saving shot, the one you must not miss or delay. Reject any features or modifications that interfere with it. For example, a red dot sight may do you some good, but a sniper scope is the wrong idea. Hanging a bipod on the gun will slow you down when you need to be fast. Think lean and quick.
To my way of looking at things, the carbine is a short range weapon first and foremost. I think this way because short range defensive emergencies are far the most common kind, so your weapon should be highly suitable for such use. The carbine's ability to reach out to distances that a pistol or a shotgun cannot match is merely a bonus. A defense gun that may need to serve for near or far is much more likely to be needed at near distance. A properly set up carbine deals with that reality by being optimized for close work, without ruling out longer distances.