True or false: The best handgun in a given caliber is less powerful and accurate than the best rifle firing the same round.
A handgun is more powerful and accurate than a thrown rock,a thrown spear or an arrow, but they have inherent structural limitations, most notably the short barrel, that make them less powerful than a rifle.
It's relative; "not very powerful or accurate" doesn't mean I want one fired at me, or that I'd fire anyone or anything I don't intend to kill deader than Caesar.
Excellent point and of course the answer to the question posed is TRUE. I was taught that the true purpose of a handgun is to give you time to fight your way to a battle rifle. Having said that, I also know there are very few people who can shoot up to the capabilities of most brand name firearms, be they rifle or pistol. Centerfire or rimfire. I once had a First Sergeant who could score "X" hits on a bulls eye target with a 1911 45 at 75 meters. Could do it all day long. The hold over required is similar to your average mortar. What's the old saying? Beware the man with one gun....He likely knows how to use it!
It's just that in the original post I responded to, it seemed to me you were equating modern handguns with their 18th century ancestors. They really have come a long way since then. While a Walker 44 certainly will blow a bigger hole in flesh than a 9mm Glock, I don't think many folks will argue the Walker is preferred to the Glock for self defense by the masses.
Generally true, but not absolutely. I've seen tests done where they started with a very long barrel, measured the velocity of a few rounds, and then shortened and re-crowned the barrel. With a really long barrel, you lose muzzle velocity due to friction. But that's pretty long. Generally a rifle shooting pistol caliber ammunition will have a slightly higher muzzle velocity than a pistol with the same ammunition. Of course operating mechanism matters too. Semi-autos, either rifle or pistol, recoil or gas operated use some of the energy of the fired round to operate the mechanism. Revolving cylinder weapons (there once were revolver rifles, I've seen examples in the Texas Ranger Museum in Waco), lose something in the cylinder to barrel gap.
I think the tests I mentioned above were done with Thompson-Contender, but I could be misremembering that. Neither effect is present with a break action.