Something is funny there. There should be little or no difference in
the "effort" required by a carbide cutter versus HSS. If anything, the
HSS should require slightly less effort, given equal sharpness.

The only reason to go with carbide when cutting brass is if you're
burning your HSS cutters. This is extremely unlikely.

There is one other potential issue, however: Carbide is stiffer. If
the flexibility of the cutter itself is contributing to the chatter,
carbide could help.

--
Ed Huntress

The tool has 22mm of 4mm length, so I'm thinking deflection is a suspect, and a shorter (and carbide) tool should help. As far as carbide vs. HSSE, so far I've noticed that it plunges with much less strain, but I haven't used it enough for profiling to draw a conclusion.