Been there.. It wasn't a buzz in the traditional sense as more of a dullness at some frequencies followed by interference buzz at others. The brass ones are thinner than the wooden ones Albert made for it. They drop in and the string tension holds them there, so quite the opposite in fact.

Clockwise moments equalling anti Clockwise moments and all that, the relatively large amount of mass added close to the fulcrum point (saddle) on the other side as it were does alter the string characteristic as the m x d on the other side alters.

For most guitars, this would indeed be snake oil, as the relative change in mass of the bridge and the rigidity of different bracing styles more than makes the small extra mass irrelevant. I proved this by taking out the tusq pins in my Rainsong and trying the same experiment. No difference... Remember the Rainsong has no bracing and the rigidity of the carbon fibre does the work so brass pins shouldn't make a bit of difference and indeed they don't.

I don't buy into different tones from different material of pins but laws of physics dictate differences between certain variables and the extra mass from brass on very lightly braced guitars with small light bridges should have an effect of the decay of the string force and in this case did, enough to overcome a small but annoying problem. (Putting 012s on helped too but not enough, and I want 011s on this anyway.

Incidentally, I sprayed the cheap Chinese steel ones to match that old Jim Harley I have. They look good but make bugger all difference to the sound.....