What I've always thought would make an interesting alternative-history story would be if the Native Americans (or aboriginals in any place really) had something akin to a modern compound bow.

I've been shooting bows since I was six. I've also fired matchlock smoothbore guns. The matchlock is more powerful, but less accurate, slower to fire, noisy, it takes some setup before you can fire it the first time. Compound bows are crazy accurate in the right hands, and some can launch an arrow weighing 40-50 grams at 100 meters per second. Add a sharpened tip and it will penetrate a lot of armor, too.