I asked on the gunsmithing side and it just crossed my mind to ask here.

I  just made an aluminum rib for a shotgun and serrated the top side of it at 50 LPI.

I was going to use a spray on it but found it was filling in the serrations.

Has anyone used Birchwood Casey Aluminum Black with good results?
Or any other home method?

This is raw aluminum.

I have not found a local anodizer or have the ability to do a home anodizing  job.

Thanks.

Update: Got some tried it, poor results waste of time and money IMHO!

I used BCAB to touch up some rings that I lapped.
It's not a hard coat by any stretch. Even over a small area it mottled a little and came out uneven.
None of that can be seen once the scope was mounted.
I just didn't want bright edges peeking out around the tube.

Easy to apply, reacts pretty quickly.
Needs a water rinse to neutralize and clean away.
Does the job but I wouldn't use it for anything other than touch up.
You might want to try Duracoat, Alumahyde or one of the other paint type finishes.

OP,
I've had the BCAB work very well on some aluminum and only so-so on others. All were equally clean. Don't know why.

maybe not all Aluminum is equal - alloy or some such