If you're talking about firearms, you have to know what the definition of "firearms" is according to the Uniform Firearms Act (UFA).
§ 6102. Definitions. Subject to additional definitions contained in subsequent provisions of this subchapter which are applicable to specific provisions of this subchapter, the following words and phrases, when used in this subchapter shall have, unless the context clearly indicates otherwise, the meanings given to them in this section:
"Firearm." Any pistol or revolver with a barrel length less than 15 inches, any shotgun with a barrel length less than 18 inches or any rifle with a barrel length less than 16 inches, or any pistol, revolver, rifle or shotgun with an overall length of less than 26 inches. The barrel length of a firearm shall be determined by measuring from the muzzle of the barrel to the face of the closed action, bolt or cylinder, whichever is applicable.
What is Section 6102 talking about? It's talking about handguns (pistols or revolvers), short-barreled rifles (SBRs) and short-barreled shotguns (SBSs). It is not talking about your normal, run-of-the-mill rifle or shotgun (and a carbine is considered a rifle).
Then we pop to Section 6106 which states you essentially need a License to Carry Firearms (LTCF) to transport the preceding items when in (or on) a vehicle (and a "vehicle" can be an automobile, truck, tractor, horse, bicycle, moped, motor cycle, skateboard, or even a Segway).
§ 6106. Firearms not to be carried without a license.
(a) Offense defined.--
(1) Except as provided in paragraph (2), any person who carries a firearm in any vehicle or any person who carries a firearm concealed on or about his person, except in his place of abode or fixed place of business, without a valid and lawfully issued license under this chapter commits a felony of the third degree.
(b) Exceptions.--The provisions of subsection (a) shall not apply to:
(11) Any person while carrying a firearm in any vehicle, which person possesses a valid and lawfully issued license for that firearm which has been issued under the laws of the United States or any other state.
Ah, but what about your normal, run-of-the-mill rifles or shotguns? Well, if we look a little bit further down in the UFA, we find:
§ 6106.1. Carrying loaded weapons other than firearms.
(a) General rule.--Except as provided in Title 34 (relating to game), no person shall carry a loaded pistol, revolver, shotgun or rifle, other than a firearm as defined in section 6102 (relating to definitions), in any vehicle. The provisions of this section shall not apply to persons excepted from the requirement of a license to carry firearms under section 6106(b)(1), (2), (5) or (6) (relating to firearms not to be carried without a license) nor shall the provisions of this section be construed to permit persons to carry firearms in a vehicle where such conduct is prohibited by section 6106.
So, if you're transporting a rifle or a shotgun in a vehicle, or a handgun without an LTCF under its exceptions, it has to be unloaded (and its cartridges located in a separate container.
If you have an LTCF, you can transport your handgun (or SBR or SBS) loaded or unloaded. Whether you have an LTCF or not, regular rifles or shotguns cannot be loaded.
