I've been there.
depending on what kind of case trimmer you have, you can get a "hollow pointing kit"
You put the loaded case in the case trimmer. Where the pilot normally goes, you place the "kit" which is only a SMALL center drill...
If you have a case trimmer, but can't find a hollow point kit, just mic the shank of your pilot, and get you a machinist's center drill (nothing lik a normal twist drill, don't go there) that snugly fits the hole in the shaft.
i know it has been done, and can be done. I'm not saying it is safe or advisable, but wanted to answer your question, and not tell you waht to do, what not to do, or waht is worth what.
I like it when people answer my direct questions directly.
Experimenting is the interstate to wisdom, depth of knowledge, and perhaps missing fingers, eyes or death if done recklessly.
As a fact the only way you will push the lead core out of the jacket is if:
1. you drill a rediculouly huge hole in the nose of the jacket and or
2: if your shooting a screaming hot load, or really long barrel, or both- which causes enough bullet heat to liquify the core. you'd know if your liquifying the core with your laods prior to hollow pointing beacuse that is what causes bullets to desinigrate* in mid air.