It looks like it was made for the marlin lever action 35, has a 200gr projectile, I would expect its called heavy, due to a heavier than normal projectile or being fired by a bit hotter than normal load, or both, which was the reason for the labeling on the packages that says specific rifles. Other rifles at the time may not have been able to withstand the chamber pressure. A heavy weight projectile without a larger powder load wouldnt increase chamber pressure though.
All of that is speculative, as I have no specific experience with that gun or ammo.
There are three different rounds. The "heavy" one is 220 grain and looks like the fattest projectile of the three. The Hornady round has a pointy plastic tip, and it's 200 grain. The Remington "high velocity" rounds are 150 grain with a pointy lead tip.
a 150 gr is lighter than a 220 gr projectile. I would suspect there is a bit heavier load behind it to propel it sufficiently.
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