That bullet didn’t fail , deer dead right there. A fail is when it’s hit proper and it runs and you don’t find it. Lots of the cup and core bullets perform like that and that’s normal , a failed bullet would be the likes of a bonded core one flighting to pieces .
SSTs are pretty explosive but seem to get the job done ok so if they work for you don’t try and fix it you may end up with something worse.
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