I believe your question is that if you have it registered as a handgun, do you need a Sportsman permit if it's wearing a rifle stock and a 16"+ barrel? My answer is yes, the ATF has you on a technicality if you were to be involved in a tresspass crime or shooting accident with your firearm while hunting. I can't really see any other reason for you and your firearm to be investigated. I have a concealed carry permit so I cover my butt, regardless of what I hunt with. The sportsman permit only allows you to have the weapon outside your garments but a concealed carry permit allows you to have a handgun holstered inside your hunting jacket. I have 7 frames now and without research, I have forgotten what they were registered as so I just have a carry permit. Going from handgun to rifle is fine, a.k.a. carbine kit. Going from rifle to handgun I supose is the No No. Also a good point about the minor carrying the carbine too. Since your gun was registered as a handgun, I would imagine all rules apply, including transport laws.