Complex sentence: The percussion ignition system was more weatherproof and reliable than the flintlock, but the transition from flintlock to percussion cap was a slow one, and the percussion system was not widely used until around 1830.
Split into simpler sentences: The percussion ignition system was more weatherproof and more reliable than the flintlock. The transition from flintlock to percussion cap was a slow one, even at that, since the percussion system was not widely used until around 1830.