If they were used as arrowheads, as they appear to be, then perhaps they were affixed to a shaft with glue, resin or even wax that filled up the void and supported the long tangs against the shaft. The end of the shaft of course would have rested in the inside V so that it could drive into the target. Pulling it out would leave the point embedded and likely broken into whoever was shot with it. That makes me think they were not hunting points, but war points. Just a idea, not even a theory...yet.
If I could make one, I'd try it, but those would be hard to make, for me anyway.