I buy a lot of Lapua Cases from many years ago including their cardboard boxes and have never seen a "Piece of Foam" in any of them. Latest purchases were this year.
Blue plastic box with the case holder you need to remove from the top lid section.
You lost me with the Foam story as I have never seen it. I either give the boxes away or throw them away as they don't float my boat for ammo storage but rather everything I have is the correct size MTM Case Box.
Palma cases as far as I know are a different story to a normal .308 case being for target use with the small rifle primers, don't know of any other difference. I don't have a .308 but quite a bit of the .243 Lapua cases that I have weighed... I don't work in grams, rather grains that I weight sort my target cases. Over different batches of Lapua cases in a few different calibres the weight difference is normally in the neck area thickness.
BTW... Do not ever Ream or touch the small flash hole in the Lapua cases or you will destroy the design.. just a hint in case.
For weight .04g is 0.6 grains not much but I sort mine in increasing weight and use them that way. To go further is to better measure by case volume.
I use a Gempro 250 Scale that measures to 0.02 grains or one granule of AR2208 powder.