A handgun chambered with rifle rounds or shotgun shells ...?

NO. Pistol bullets are, by definition, less powerful than rifle bullets. The only pistol bullets that even remotely make sense in a rifle are .44 magnum and 10 mm and the like.

Those might be useful for light, handy, short range, 'brush guns'. The shape of the bullet makes very little difference compared to weight and velocity. .308: - 2800 FPS - energy: 2600 Ft.

/lb. S 45 ACP. : - 800 FPS - energy: 410 Ft.

/lb. S (Your english is pretty good).

No the stopping power compared to a full power rifle round is not even close. The 50ae would be okay in a rifle, but it still wouldn't have .308 stopping power. It would probably be better than a 5.56x45mm.

It is a combination of caliber, velocity, and bullet weight. For example, a 45auto round may be 30-40 percent heavier in terms of bullet weight than a .308 round, but the .308 round goes around 3X as fast meaning a lot more energy. The .45 round would gain some velocity out of a rifle barrel, but the .308 round is still far superior.

Read some of John linebaugh's writings(on his website custom six-guns) about the strongpoints of some handgun calibers. He talks a bit about similar topics. Technically if you go up to 500s&w(a very big handgun round) you can get serious performance out of a rifle that puts a lot of other rifle calibers to shame, but this is more of an exception and not the rule.

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