LAR-15
I am going to say, broadly, that which makes a firearm "sporting" would be its intended use as designed by the manufacturer. Today shooting sports are far broader than even 20 years ago.
I will postulate that there is a wide gray line between sporting and let's call them "defensive" firearms.
I am going out on a limb here and say that very few handguns would be of the sporting variety based on where I am going...Contenders, S&W .500s...those kinds of things are "sporting" as would be purpose-built target pistols both center and rim -fire. I would submit that a Glock or an XD would be a "defensive" firearm...purpose built for law abiding citizens to use in the lawful defense of home and family. Ditto for AR-15, Mossberg 590, AK clones.
Of course one could certainly argue that any sporting firearm would server to defend and of course millions hunt, target-shoot, control varmints, and plink with defensive arms...how many coyotes have fallen to the AR-15?...a lot! How many burglars have been scared away by a single shot 12-ga or a 30-30?...a lot!
I am afraid even though we have a God given right to defend ourselves (and a right supported again by the Constitution), the use of the the word "sporting" is going to be used against us in attempts to limit what we may use to defend ourselves or for that matter, use for sporting purposes.
Bottom line, and please feel free to disagree THR members, but the anti's are going to classify "sporting" as anything big, wood, single shot or repeating (exclusive of semi-auto), with a low capacity, non-removable magazine. Your Model 94 or your Savage 99 is probably safe from the anti's for the time being...beyond that...watch out!