I've presented this style Slug before on this and other forums, along with my other style darts. I was informed that they would not be legal at Apoc (or any other East Coast war). The write up no longer exists in this forum but is up in others
I believe they are the same bearings (Canadian variant).
In my informal tests, regardless of dart head, punching through card board boxes eventually
caused the heads to separate from the foam. However, the bearings that did separate did impact and sometimes punched through the second layer of the cardboard box. The other type dart heads did not seem to have the same affect.
That being said, direct
impact against my heavy bag (more similar to the human body than a concrete wall) did not cause any dart head separations by any of my dart types.
But it's the glancing hits, like those off a blaster hit, which are most prevalent here. Similar to cardboard, indirect hits or glancing hits, have the potential of torquing the foam enough to cause separation. Especially at the velocities we can generate at shorter distances.
Washers and other dart head types loose kinetic energy and momentum quickly once separated from the foam but the bearings tend to carry much of their kinetic energy after being separated.
hits did not cause separation but glancing hits did appear to be more susceptible to breakages. I cannot give an exact percentage but it was pretty low. I don't believe it carries enough residual energy to actually hurt anyone upon regular impact (after separation) but it is small enough to sneak past some of the openings in some peoples protective eye ware. Which is a consideration for the war host.