What is the effect of testifying under a grant of use immunity before the very federal jury which indicted the appellants?

Both appellants testified under a grant of use immunity pursuant to 18 U.S.C. 6002 before the very federal grand jury which indicted them. The claim now is that it was a violation of Kastigar v. United States, 406 U.S. 441, 92 S.Ct. 1653, 32 L.Ed.2d 212 (1972), for the same federal grand jury which heard their immunized testimony to indict them. We so held in United States v. Hinton, 543 F.2d 1002 (2d Cir. 1976), with respect to a substantive offense which was not perjury. Appellants argue that the Hinton rule, which was announced after their indictment, is retroactive and that it applies not only to require the dismissal of the substantive counts but also of the perjury and false declaration counts.