Like most of the 6mm pellets... Impacts will destroy most external detail parts (headlights, handrails, etc...) Even the 6mm chalk rounds will cause damage to the detail parts (aka plastic tools, tow cables, fire extingushers, etc...)
at the low end, most HL Airsoft shoot at about 250fps (76m/s) using a 20g pellet. Some can go up to 400 fps (122m/s).