I was playing around with my fretless bass and wanted to lower the action to see how it would play and if I would get more mwah from it. So I mosey on over to the saddles and it turns out I already have them as low as they will go.

Then I remembered the quick solution is to stick a shim on the neck, right? Which means something in between the bottom of the neck and the pocket that the neck bolts onto, correct?

What's the best type of material to use? How do I cut it? How thick?

Also, I tried to "pull back" the screw for my low B string as far as it will go on the saddle, but the intonation is still off. Anything I can do about that?

People use anything, strips of business cards, bits of guitar picks... start with something thin closer to the bridge screws if you know what I mean.

And with your B, is it tapered or not? If it is not I would just recommend getting one that is and checking if that helps with intonation.

Not sure which shim material is best to reset the neck. However, I did just used a sliver of beer can aluminum to raise / reset the brass nut on my fiver!

I've had the same problem with B string intonation on a couple of instruments. Unless its way off, I don't think anybody will notice. I've actually taken the intonation spring off and cut if in half before reinstalling. The procedure allows the saddle a little more travel until you hit full spring compression.

Riis

So it doesn't matter what material I use for the shim?

By tapered do you mean thin over the bridge saddle and then thicker right afterwards? Because it's not.

EDIT: In my case it's not compression, it's going the other way. I guess I could just buy a longer screw, though. =/

Everyone has different preferences for the shim material and I would use something hard like tin or thin plastic.

And with the B, yes tapered string is the one that is thin over the saddle and then gets thicker. Since yours if flat I guess a longer screw, if you can find one that will fit is the best option.

It's weird, I just checked the other screws on the saddles and they are all different sizes. I guess my only option is to switch it out with one of the saddles that has plenty of screw left. So that won't be so bad, actually.