This is 99% invisible. I'm Roman Mars.

Let's say you lived sometime before 1860 and you wanted to fire a rifle.

First, you'd need to pour gunpowder into the powder charge to measure the amount of gunpowder you need it.

And then you pack down your gunpowder and then bullet into the rifle with a ramrod.

Then you'd pull back the hammer and take something called a percussion cap and you'd fit it on the hollow metal nipple on the back of the barrel.

Pull the trigger and...

That was one shot.

Then you had to reload, which meant pouring out new gunpowder,

stuffing the gunpowder and the new bullet down with a ramrod, pulling back the

hammer, putting a new percussion cap on the nipple and then you could shoot again.

The whole process took at least as long as it just took for me to describe it.

And as you can imagine, this was all really inconvenient if someone was shooting at you.

But then came the Winchester Repeater rifle.

That's reporter Nina Gensler-Dabs.

The Winchester 1866 repeater rifle was a thing of beauty.

Nicknamed the Yellow Boy for its bright brass receiver, the gun was sleek, gleaming, and deadly.

You could fire off 15 shots in just over 10 seconds.

And the Winchester repeater arrived on the market just in time for the rise of Western expansion.

The huge sweep of manifest destiny and people migrating to the Western part of North America.

That's Mary Joe Ignafo, a California historian at Deansa College and Cupertino.

That weapon became a source of survival and protection for people.

The next iteration of the Winchester repeater,

...