U.S. Senator Richard Blumenthal, D-Conn. on Jan. 29  introduced the "Ammunition Background Check Act of 2013," according to a statement.
The bill would require "an instant background check for the sale of gun ammunition," the statement said.
"In conjunction with introducing the bill, Blumenthal held a conference call with Brian Malte, legislative director for the Brady Campaign to Prevent Gun Violence, and Robyn Thomas, executive director of the Law Center to Prevent Gun Violence. Both organizations support the bill," the statements said.

Read documents Blumenthal released here (all information in this post was contributed):

Ammunition Background Check Bill by

And here:

Ammunition Background Check Bill Summary by