Another Culverhouse try on 68 minutes secured the bonus point.
Westcombe crossed on 70 minutes through Keiran Thompson and Benjamin Fryatt dotted down as the game drew to a close. Both those tries were coveted by Nathan Wyman.
In between, Ciaran Mcgann had added five points for Raiders, again converted by Teasdale.
Raiders won 33-14, avenging a 25-19 loss away at Westcombe earlier in the season.

They remain 11th in National 2 East.