As a sheep rancher, I have access to lots of good quality merino horn and want to cut scales off of them.
So far I have used a meat bandsaw (only bandsaw I have) and a small angle grinder with limited success as the shape is asymmetrical. I tried cutting it into 6" sections first too.
Even then, the slabs are very uneven and take a lot of grinding to achieve a uniform thickness.
Question: what else can I use? Jigsaw? Handsaw? I would have to buy a jigsaw.

Any advice on working with horn is appreciated as the internet has little to offer.

I would spend a little time and build a jig that you could clamp the piece of horn securely. I would then use a bandsaw for cutting.

I use a bandsaw to cut slabs from moose horn drops I find. They are never uniform, as the horn tines are not uniform. I put them on a beltsander to even them up and flatten them out for epoxying to the knife. I think you could get them close with your angle grinder. Then, with a sheet of sandpaper on a hard flat surface, finish flattening them by hand.

Thanks for the tips and I will see what I can do. I also think that I must separate the horn from the bone first to make it easier to saw.

Yeah, bandsaw. Follow the contour and get the thickness. Boil in mineral oil put in a vise while hot to flatten. Get a belt sander to finish flat.

Thanks Jerry. I will give it a go.

I was going to suggest boiling.