Sorry, I missed that you said the material was brass. A high helix is not likely to be the answer, because brass has a tendency to cause the tool to 'hog in', overload itself and wreck something.
For the best cut while drilling (plunging) the brass or bronze alloys, the tool flute should have no helix at all. If you have a tiny wheel on a Dremel, you can get the wheel inside the flute at the sharp edge at the cutting end, and grind it flat, with a flat face parallel to the axis of the tool. This flat does not need to be extremely wide, probably .020" wide would be sufficent. It should be accurately flat, and should not round over the edge. Even presented to the work at a 90 degree angle, an edge will still take a chip if it has clearance underneath.
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