A rotating assembly of a gas turbine engine, comprising: a first rotating component (60, 86); a second rotating component disposed radially inboard of the first rotating component, relative to an engine central longitudinal axis; and a seal assembly configured to seal between the first rotating component and the second rotating component, the seal assembly including: a shuttle disposed on a radial outer surface of the second component and freely axially movable along the radial outer surface; and a piston ring seal retained in the shuttle and engaged with the first rotating component; a first axial stop and a second axial stop at the second rotating component between which the shuttle is axially retained; wherein the shuttle comprises a forward axial leg and an aft axial leg extending from the shuttle base and defining a shuttle pocket therebetween and into which the piston ring is installed; and wherein axial motion of the first rotating component (60, 86) relative to the second rotating component urges movement of the shuttle along the radial outer surface of the second rotating component, while the position of the piston ring seal remains stationary relative to the first rotating component; characterized in that the shuttle further comprises a forward arm extending axially forward from the forward axial leg and an aft arm extending axially aft from the aft axial leg; the forward arm at least partially overlapping one of the first axial stop or the second axial stop and the aft arm at least partially overlapping the other of the first axial stop and the second axial stop, wherein the first axial stop is a shoulder formed on the second rotating component, and the second axial stop is a retainer secured to the second rotating component. a first rotating component (60, 86); a second rotating component disposed radially inboard of the first rotating component, relative to an engine central longitudinal axis; and a seal assembly configured to seal between the first rotating component and the second rotating component, the seal assembly including: a shuttle disposed on a radial outer surface of the second component and freely axially movable along the radial outer surface; and a piston ring seal retained in the shuttle and engaged with the first rotating component; a first axial stop and a second axial stop at the second rotating component between which the shuttle is axially retained; wherein the shuttle comprises a forward axial leg and an aft axial leg extending from the shuttle base and defining a shuttle pocket therebetween and into which the piston ring is installed; and wherein axial motion of the first rotating component (60, 86) relative to the second rotating component urges movement of the shuttle along the radial outer surface of the second rotating component, while the position of the piston ring seal remains stationary relative to the first rotating component; a shuttle disposed on a radial outer surface of the second component and freely axially movable along the radial outer surface; and a piston ring seal retained in the shuttle and engaged with the first rotating component; a first axial stop and a second axial stop at the second rotating component between which the shuttle is axially retained; wherein the shuttle comprises a forward axial leg and an aft axial leg extending from the shuttle base and defining a shuttle pocket therebetween and into which the piston ring is installed; and wherein axial motion of the first rotating component (60, 86) relative to the second rotating component urges movement of the shuttle along the radial outer surface of the second rotating component, while the position of the piston ring seal remains stationary relative to the first rotating component; characterized in that the shuttle further comprises a forward arm extending axially forward from the forward axial leg and an aft arm extending axially aft from the aft axial leg; the forward arm at least partially overlapping one of the first axial stop or the second axial stop and the aft arm at least partially overlapping the other of the first axial stop and the second axial stop, wherein the first axial stop is a shoulder formed on the second rotating component, and the second axial stop is a retainer secured to the second rotating component.