They don't just want that ban, they want to widen it. Greatly.

As in 'just about every centerfire rifle ammunition made'.
... U.S. Rep. Steve Israel (D-N.Y.) announced that he intends to introduce legislation to “extend the definition of armor-piercing ammunition to include all bullets that can pierce body armor and be used in handguns.”
And you can bet he'll include single-shots like Contenders in his definition of 'handguns'.