Tell them to oppose HB 768, which would require registration of every gun, with the registration being renewed every year, along with a background check and fingerprinting every year. $10/gun per year, which of course can add up depending on the number of guns.
https://www.wpxi.com/video?videoId=9...deoVersion=2.0
While it is doubtful that it will get out of committee in PA, given the current climate, I suggest not being complacent.
Edited to add: Realizing that I am preaching to the choir, we all know that registration serves no real purpose unless and until confiscation becomes a reality, at which point it makes confiscation feasible.
Also, while I cannot recall the name of the case and do not have time to look now, I recall a US Supreme Court case holding that requiring criminals to register their guns is a 5th Amendment violation. While most gun control only affects those who obey laws, registration is particularly bad in that regard.