I had some issues priting the powder part of the .308 cut away model by Johnny No. 5 (https://makerworld.com/en/models/187510#profileId-300020). At about 3/4 of the height it would separate from the printing bed and fall over. It looked like the textured bottom surface was not providing enough contact with the printing bed. So I sliced off about 0.3mm of the bottom, resulting in a smooth surface. This solved my printing issues.

I had also experimented with upscaling the powder part from the 9x19 model, but that didn't work due to the taper at the bottom of the .308 case. But I noticed that the 9x19 one was apparently a compressed version of the .308 one and I liked the larger grain texture better. So I scaled up the 9x19 one again (Z-axis only) and cut it at the correct height.

I'm sharing this here, in case anyone else encounters the same issue.