Instructions
Select how you are going to employ your carbine
If your use is for home defense then a short and handy weapon is ideal as you may have to store it in a small area and use it to clear tight hallways. These simple home defense weapons can even be dual-purpose hunting or sports shooting firearms with little or no changes required. If your rifle is to be used for police or force protection employment then it should be a more purpose-built platform meant to hold up to repeated all-weather use and able to withstand the hard knocks of being placed in and out of patrol racks and car trunks.
Decide your overall price range for your rifle project. The most economical light tactical carbines are of the SKS-type. These can be had for around $100 for surplus imports from the former Yugoslavia and modified cheaply with aftermarket stocks and a lower-end reflex sight if desired. More moderately priced rifles like the Rossi and Puma lever-action carbines and Ruger Mini-14 can be purchased from between $300-$400 and have the benefit of appearing more like a traditional hunting rifle. Higher-end weapons include the Beretta Storm series, SIG 550 series and AR-15 platforms that begin at the low $600's and quickly work up to two or three times that amount depending on all of the bells and whistles. These higher end weapons, while they are purpose-built for tactical situations can sometimes be price-prohibitive.
The caliber of your tactical carbine should be a basic building block of your design. By definition the light tactical carbine would be more of a carbine-caliber weapon (i.e. under 7.62x51 NATO/308 Winchester). The majority of these weapons would be in the popular 5.56mm/.223 caliber such as the Sig Sauer 550 series, various AR-15 series and the Ruger Mini-14. Smaller pistol caliber rifles chambered in .45 ACP, .40 S&W or 9mm parabellum such as the Ruger PC-9 and Beretta Storm series have lighter recoil and are often shorter and more handy weapons but are however limited in range to under 100 yards. If using the lever-action weapon there are many models available from Rossi, Henry and Marlin that are chambered in the more traditional revolver caliber 38 special/357 magnum and 44 magnum. The new 6.8mm round is ideal for engagements up to 300m but the platforms that accept it are limited.
If you are going to use your light tactical carbine for home defense then optics anything other than ghost ring fixed sights or night sights may be impractical unless you check your firearm often. If you are in a law enforcement or force protection sector then a more durable ACOG, Trijicon or EOTech type reflex sight is ideal for quick target acquisition. Several of these powered optics with full-tube designs can be used accurately by a trained marksman out to 300 meters with a visible approved target. Good powered optics can however be very expensive, often more than the price of the rifle itself.