SST’s are very similarly constructed to Interlocks, but with a non-deforming polymer tip instead of a soft lead tip. Both are non-bonded cup and core designs with an “inter-lock” ring inside the jacket, both spitzers - but when an Interlock runs into something, its soft lead nose deforms ever so slightly, retarding the initial expansion. The SST, alternatively, has a hard polymer tip which remains rigid, instantly initiating expansion upon contact, driving itself back into the bullet core. So one is a charcoal grill, one is a charcoal grill with match-light charcoal - just a little easier to get started.
That difference can be enough to create a dramatic difference on how they perform on game. I wouldn’t necessarily say the Interlock is good for any game for which the SST is not, but impact velocity and range might sway my decision between the two.
Given the context of elk hunting with a 300win mag, neither bullet would be my choice for elk, and neither bullet would be my choice for 300win mag. If I’m elk hunting, it means I’m out of state, with limited time and opportunity to hunt, and probably a lot of money wrapped up into the hunt/tags/travel, so I’m not taking any chances. The 300win mag is too much horsepower for either of these bullet designs at short ranges without risk of bullet failure (excessive weight loss, jacket & core separation). Just not a chance I take.