The biggest problem is that most rifles cannot be safely carried with in the ready to use position. By that I mean, I pull the trigger, the perp drops or I pull the trigger a the hammer and boom the perp drops. Also, what about Short Barrels. For example, what about 14" Shotguns or M4s. A rifle is too cumbersome to be a practical carry weapon. Most rifles with hammers that can be "De-Cocked" as in tapping the trigger wouldn't cause an accidental firing are single-shot. Single-Barreled Shotguns and Winchester Carbines could be carried in a ready to use fashion. But, exactly how useful is a one-shot gun in a firefight. Show me a select-fire rifle that can be de-cocked without firing and then recocked in an instant and I might consider. Also, they would have to allow me to have Barrels shorter than 16"/18". Possibly eliminate the overall length requirement. This would allow for the creation of more effective (Carry) Bullpups. Then again it is much easier to get the drop on a guy with a rifle since it is not concealed from view. A concealed weapon is more effective since the perp doesn't see it coming. Possibly, a Select-Fire Rifle with an action similar to a pistol. Such as, I pull the trigger, then the bolt carrier pushes a hammer (outwardly visible) back into a cocked position. Then, the user could hold the hammer and pull the trigger so that it could be carried. Possibly, if we were allowed to carry a sidearm that could be used in order to hold 'em off until I get my rifle. As once said "A sidearm is for holding 'em off until you can get to a rifle" Also, there are many places I can't take my rifle.