Inletting black is a fairly basic item; now Brownells and Midway seem to have dropped it from their lineup. I wonder whazzup?

Doesn't work on black plastic stocks?

Try TOW for Jerro's

https://www.trackofthewolf.com/List/Item.aspx/1021/1

or
Boyds for Miles Gilbert

https://www.boydsgunstocks.com/productdetail/a20005_wheeler-inletting-black-1-oz-wapplication-brush

Thank you Steve.

Years ago I was discussing inletting with marshgurl and he suggested that lipstick was superior in every way. A quick test of that proved him right. Works pretty super for fitting metal as well. Not to mention waaaay cheap. The Revlon Lipglide red stuff that I got at Walgreens is many years old now and still hasn't run out.
Make your life easier -

Is Prussian Blue still available. I have a bottle that I got many years ago.

Answered my own question: Permatex® Prussian Blue is available for metal work. It now comes in a tube. My bottle is a liquid. I have used this on metal and on wood. Although it does stain wood.

I've been using (Non-Drying) Prussian Blue and a series of used toothbrushes for four decades. A total of about three tubes...and the third is still more than half full.

I have always used rouge that ladies use for face make up.
I have used it for inletting also (ha ha ha)

I usually mix oil(usually way oil)with the Prussian Blue, it lightens it up, and slows drying. I use either an artists or acid brush ( I really use smoke as much though). It is all messy.
Mike

Doesn't have to be messy. Salopian's rouge (((you have to remember that he is English {;-) ))) and the lipstick are not. I suppose that there may be situations where they may not work but I've not encountered them or can think of any.

I vote for lipstick.