there are a few postings for the advice you seek in the carbine section of the forum.
The forum search function doesn't turn up much. (yeah, I actually did try searching before I posted.
i made my own, as i live in this hellish state. what i did was order the large bullet button, sand blasted it and painted it black. drilled a small hole in the middle. put spacers (washers) in the back of the release, to make it stationary. it works great. hope this helps!
I'm having trouble visualizing what you're describing. But I think I can figure it out with a bit of work.
Any other suggestions?
Peace favor your sword