I tried searching online and did not find much/conflicting answers. Hoping someone here might have personal experience.
I have a a gun that was hydro dipped and it is very gaudy, so I am stripping it off to restore it to original. It is a all steel pistol and it has what the company says is black oxide finish on it (which from what I read online is basically the same as bluing).
I have soaked a couple of the parts in a sealed jar of acetone. The actual hydro graphics started coming off almost instantly, and after a few min, was just floating in the acetone. However the underlying paint is still there. I put a couple of the parts in another jar filled with lacquer thinner and left the others in the acetone.
They have set in the jars overnight and while the graphics are gone, the underlying paint is still there and has not appeared to change.
My next step is it use actual paint stripper, however I worry about it harming the original finish/black oxide/bluing.
The underlying paint is white (the gun is supposed to be almost black)
Before I soaked them in the acetone, I started out with a rag and some carb cleaner and the rag had white on it, so the paint was coming off a little with the carb cleaner and rubbing with a rag. So I do not think it is something like cerra coat. But the acetone does not seem to be doing as much.

I do not know what company (if it even was a company) did the hydro dip, and I do not know the process they used or what paint they used. I would really like to remove the paint without harming the original finish. I am aware there might not by any alternative and may have to have the metal refinished. However that is last resort.

I bought a couple rifles in the past (not at the same time) that were spray painted and both of those, acetone and a toohbrush took the paint off super easy. This stuff seems a little more resilient than regular paint.

I would not put that stuff any where near my gun, paint stripper can melt plastic so I would think it will ruin the blueing.

Yes

There is no plastic to worry about on this gun.

So anyone have any suggestions for removing paint that will not harm/remove bluing/black oxide, when acetone will not do it.

If laquer thinner didn't affect the paint, stripper might not either. Try applying it to a small part first. At this point, saving the bluing while removing the coating might not be possible.

Well the small parts I have had in the jars were the aluminum scope rings. I figured I would start with those since they are easy to replace if I screw up.
I dumped the jars out into a bowl and using a small tooth brush sized wire brush, gently started brushing them. I figured I did not have much to lose at this point.
The paint started coming right off. Only issue was I found out they had been bead blasted before they were coated.
So I am not sure if only the anodized aluminum was bead blasted to help it stick to them (never tried painting anodizing, so not sure how well paint sticks to it) or if everything was bead blasted.

I had read about some places bead blasting before hydro dipping, so it was not something I would be completely surprised by, and knew there was a chance of it before I bought it.
Once I got it, there are several parts that was taped off before painting/coating and the original finish is there. So at this point I have no idea what to expect.
I found a stainless steel pan that fits the parts, so I am going to soak them tomorrow and see what happens.
I plan on getting a stiff nylon bristle brush and starting with that first, then moving on to the steel brush after if it is not stiff enough.

Well I put the parts in the stainless steel pan and covered them with acetone. I was going to leave them soaking for a while but the graphics and the paint started to wrinkle up almost instantly. After about 60 seconds I was able to just brush it away with a old tooth brush.
Unfortunately, the parts were bead blasted before they were painted.
But it is not the end of the world. Like I said, I knew when I bought it, there was a chance if had been. However even with that being done, it is not anything that can't be fixed.
Gonna call a couple local gunsmiths and see if they do black oxide and what they charge. If no luck local, I will looks abroad.

sandblast and Cerakote.   Be done with it.