I have two MC-462A units. I extracted all the pins from one unit. Yes the perimeter of the aluminum pins shear a little bit during press fitting. Of greater concern is the fact that under every pin is a small area in the bottom of the holes where the pins do not insert far enough to occupy. IE there is a small air bubble under the base of every pin. The HSF performs amazingly well, considering these small air bubbles, but it makes me wonder if they could be even better if the pins were in contact with the entire surface area of the hole. Right now, I am working on a long-term experiment of substituting copper-clad aluminum pins for the all aluminum pins. The hypothesis behind this is the fact that the area of the pins, where they contact the copper base, being copper clad, will benefit from less thermal resistance, yet the aluminum core will allow them to give up the heat without as much of a fight like you would see if the pins were solid copper.
The pins I am using are tapered on the ends to confirm exactly to the form factor of the holes, so that when inserted, they touch more of the surface area in the holes. Along with this shape factor, each pin has its inserting end tip dipped in Arctic Silver. As busy as I am right now, this will take some time to consummate, but I expect to be done by mid-summer.
Here is a cut-away of these special pins.
Hoot