Welcome aboard, you will find GBO has great people and can get you answers to all your questions.
Look through the FAQ section. 44 Mag barrels produced in 2007 and later have smaller bores. So if the serial number prefix is HX, NX, NY, HY, CBA, CAC or later then you have a 44 with the proper sized bore. Again, look in the FAQ section for a clarification. I have an HX and it shoots .429 - .430 factory loaded bullets just fine. Read the FAQ, even if you have no problems, it is a good read and gives you a lot of insight on the Handi rifle. Good Luck and Good Shooting