I'd say your surmise is a pretty good one. Barnes originals are advertised to be a pure copper tube filled with pure lead. It wouldn't make sense for them to produce a bullet they identify for a 30-30 and build it too tough to expand at that round's achievable velocity. Never say never though as Hornady did that very thing with a 220 gr interlock FN dedicated to the 375 Win. They kept it in production for a long while before it was discontinued . Barnes also advertise the original to achieve 2X expansion.--cb
