Which part of a modern firearm has the same function as the lock on a muzzleloader? safety trigger action barrel?

On a modern firearm, the feature that functions like the lock on a muzzleloader is the safety. The safety was added to modern guns to prevent them from accidentally firing, although it should be noted that a safety is a man-made mechanical device which makes it subject to failure at times.

The soviet union beat the us to the first successful launch, with the october 4, 1957, orbiting of sputnik 1, and later beat the us to have the first human in earth orbit, yuri gagarin, on april 12, 1961. the "race" peaked with the july 20, 1969, us landing of the first humans on the moon with apollo 11