Complex sentence: U.S.C.922 (r), which regulates imported rifles with certain features the BATFE defines as not being suitable for sporting purposes requires a certain number of "compliance parts" of U.S. manufacture to be installed on any modified SKS.
Split into simpler sentences: U.S.C.922 (r), which regulates imported rifles with certain features the BATFE defines as not being suitable for sporting purposes. This law requires a certain number of "compliance parts" of U.S. manufacture to be installed on any modified SKS.