In order for meat to be blood free, as the Jews and the early Christians would have understood it, one has to cut the neck of the animal and let it’s heart pump the blood out. Not hit it over the head like they do in the slaughterhouses today. Also you have to remove the veins and arteries starting at the neck working down.
The meat must be soaked in cold water so the blood does not coagulate and then it must be salted with coarse salt to draw out any remaining blood. What I just described to you is the basic processes that Kosher meat undergoes to be considered blood free as in biblical blood free. Unless you pay considerably extra for this service, you are not getting blood free meat.
FYI Kosher has nothing to do with being blessed by a Rabbi, that is a popular myth, meat must be prepared, as I have described above. You bet it takes a lot of skill, time, and cost extra to do this. Are the witnesses eating only meat prepared in this way, if not why not? What changed since ACTS was written? How can they say they abstain from blood? Just some food for thought <pun intended>.
Freeman