Complex sentence: These improvements were primarily the result of converting the rifle to the intermediate-caliber high velocity 5.45 × 39mm cartridge, in fact, some early models are reported to have been converted AKMs, re-barreled to 5.45 × 39mm.
Split into simpler sentences: These improvements were primarily the result of converting the rifle to the intermediate-caliber high velocity 5.45 × 39mm cartridge. In fact, some early models are reported to have been converted AKMs, re-barreled to 5.45 × 39mm.