Re: PA, your friend must have had pistols stolen as the PA State Police maintain a record of handgun sales. When you buy a handgun in PA you fill out the Federal 4473 and a state form. The state form goes to the PA State Police. This does not apply to long guns. In PA long guns can be sold by individuals to other individuals without going through a background check. Of course if you buy a long gun at a FFL you have to do a 4473, but no state form.
As far as PA being a SH compared to most surrounding states it's a gun owners paradise. For example with the exception of Philadelphia you can open carry w/o a permit. It's also a shall issue state.