Here's how it works.
Simple as differential calculus.
If you bought a semiauto gun between 94 and 2013 it needed to comply with the old Federal style AWB. 1 evil feature.
After PA13-3 passed, these guns were reclassified as AWs. And you were required to register them.
Since they were now AWs, a registered "post ban" gun could now be converted to pre ban configuration.
So if you have an AR of any kind that was set up as post ban and registered by 1/1/2014, then you can convert it to preban config.
If one of these guns is a .22. the smart thing to do would be to repurpose that registered lower and build a centerfire gun. Then buy a new lower and use it for the "Post ban" style rimfire gun.