Macau is a Special Administrative Region and has it's own government, own rules, own passports and a separate visa policy. Keeping that in mind you would have to obtain a separate visa in Macau.
Transiting through Beijing Airport will not be a problem as you mentioned (with the 72 hour rule which is valid for Russian citizens). Since the border control between China and Macau is well defined, Macau for all practical purposes can be considered a separate country.
This can be confirmed (albeit vaguely) from the fact that many sources (China Southern), mention a third country or region.
Foreign nationals with valid international traveling documents and air ticket for a connecting flight with confirmed date of flight and seat for a third country (region) leaving China at Guangzhou Baiyun International Airport within 72 hours
In this case Macau SAR will be counted as a separate region and a visa for there will be valid for the transit thru Beijing.