According to HKFa in ???? Ultimatum /
??? (????)

Ma Man-Chung / (???)
http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng
Peter Ma Man-Chung / (???)
http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng
Ma Wen-Zhong / (???(2))
http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng

please help to confirm. Thanks.

Not entirely conclusive to me. Some combining is probably due but

Ma Wenzhong the actor has a separate entry as mainland actor in HKFA
Additional acting credits mainland movies, tv series and stage dramas, no producing credits
http://baike.baidu.com/view/2474142.htm
http://ent.sina.com.cn/s/2009-04-24/22112490443.shtml

Blood Ritual is probably his acting credit, and also Great Jet Foil Robbery.

His personal blog w/credits (on left) - only claims Great jet Foil Robbery of HK film credits
http://blog.sina.com.cn/u/1307585970


This source list production credits for Heart of Killer and The Sniping along w/acting credits but doesn't sound definitive.
http://www.hudong.com/wiki/%E9%A9%AC%E6%96%87%E5%BF%A0


Added a few images.