@cal91,
'I am a Harbeth owner and I don't see how I could do that with the screws securing my drivers.'
As an Harbeth owner perhaps it might help to be a little more familiar with the Harbeth website?
Alan Shaw stated that it's no big deal as long as you're sensible and use no more pressure than is required to meet resistance.
Basically - Don't go mad!!
If you're really struggling I can try and dig up his exact words for you.
As for brass screws, let's not even go there!
How about simply trusting the manufacturers?
The people whose livelihoods depend upon their products.
The people who have spent a lot of time and resources building loudspeakers.
I might not like a lot of loudspeakers out there, but I'm not going to pretend for one moment that I, with my severely limited resources and knowledge, could do any better.
Seriously, if anyone is considering ruining their speakers in this way, it might be wise to contact the manufacturer first if they are of any value to you.