GLOCK 43X P80 FRAME THINGS TO KNOW BEFORE YOU BUY

I am bewildered. I bought a 22lr revolver a pair weeks ago, I needed to lengthen the barrel by about two inches so I asked where I could buy a alternative barrel to the manufactures Internet site, they reported which the gun was registered to me by the atf with a certain barrel size and if I alter that I would need a completely new serial variety.W