There are ballstic tips and ballistic tips, so it will depend which one they have been using and, particularly, which calibre.
When they first appeared they proved highly accurate in most rifles but, being designed for explosive performance on vermin they could disintegrate on heavier animals like deer, either destroying a lot of meat or leaving a horrendous but non-fatal wound.
This was most noticeable with smaller cartridges such as the ubiquitous .243.
In larger calibres, the bullets are generally much tougher and, while still expanding dramatically, are fine for deer stalking.
If in doubt, check the manufacturer’s website to find out what his ammo is intended for.