Complex sentence: Based on the.220 Russian, which is in turn based on the 7.62 x 39 mm assault rifle cartridge, the 6 mm PPC was developed in 1975 specifically for benchrest shooting.
Split into simpler sentences: Based on the.220 Russian, which is in turn based on the 7.62 x 39 mm assault rifle cartridge. The 6 mm PPC was developed in 1975 specifically for benchrest shooting.