has anyone used prussian blue or maybe something similar to fit things on an AR? I've got a grip I like but the bever tail doesn't quite fit and I'd like to work out where to take material off the grip.

this is on a DPMS pattern 308 lower and the 7.62 LaRue A-PEG grip, for the curious.

I had a black Magpul MIAD that didn't quite fit in the tail area. I used an old lipstick (because my blue is in my tools at work) of my wife's to figure the spots. So yeah, blue will work.

lipstick! I don't know why I didn't think of that.

Fitment