I’ve done a lot of pesting with a 14fpe .177 and I can tell you that expansion is a pretty much a unicorn goal. Recovered pellets of all sorts of geometries have shown very little if any expansion, despite what gel and water bottle tests say. If you can find a wadcutter that is accurate in your airgun, use it. They are devastating on small game like rabbit and squirrels, and they’ll turn a house sparrow into a cloud of feathers.
The ones I’d recommend trying are RWS Supermags, RWS Meisterkugelns (either weight), and JSB. I may have gotten lucky with the particular batch of Supermags I got but they will consistently vaporize small Mardi Gras beads at 30 yards in 3 different PCPs.
With that said, placement is the most important thing so my advice is to not get too laser focused on the idea of using a special head profile. I’m much rather have a dome that groups 3/8” than a fancy hollowpoint that groups 3/4”. At modest distances, that isn’t a compromise that necessarily applies but it becomes increasingly relevant the further the range is stretched.
