From: Richard Aiken

> But it is a fact that during WWII the Germans were well aware of both techniques. They used discarding sabot ["treibspiegel" or "thrust mirror"]
> rounds to increase the upper range limits of their flak guns, while simultaneously using the tapered bore principle to create an extremely
> lightweight (505 lbs) yet very effective antitank cannon.
>
> If the discarding sabot method worked just as well for both applications, then why didn't they use it that way?

Presumably limitations on their sabot technology; the technology is entirely extinct today, which implies that modern weapon designers don't consider it worth their trouble.

Doing the math on why a squeeze bore would actually be useful, the primary benefit is the same as for a discarding sabot round: you can use a lightweight bullet in a large barrel. The soft material around the edge of the squeeze bore round fills the same role as a sabot, it's just that, instead of being discarded when the bullet leaves the barrel, it gets compressed as it reaches the end of the barrel.