can anyone tell me why no one makes horn valves or spouts out of copper or nickel or does anyone know antone who does

braids-
Your first question (why does no one make...) may have a complex answer. I can attempt a reply, but it would help if you could explain why a valve or spout made of brass is not acceptable, as opposed to copper or nickel.

Your second question (does anyone know...) is pretty easy for me to answer: No.

If you have sufficient funds, I know a couple of machinists who might attempt the making of a valve or spout using copper. Nickel may be trickier; they would need to know which nickel alloy you would specify.

--Bob

I would think a pure copper valve of any sort would be too soft to allay wear/disfigurement. Nickel ( assuming you mean a cupro-nickel alloy, ie: German silver) would be much better. A copper/tin alloy (bronze) would have strength and great wear characteristics. But, I gotta ask why? A metallic valve on the end of a horn, even if carefully made and fitted, is a great entry vehicle for water/dampness to get into the powder. I stick with tapered wood plugs in mine, fitted into matching tapered holes, and have come through monsoon-like downpours with bone dry powder. Simple expedient: an ebony violin tuning peg with tapered shank, and a Morse taper reamer to cut the hole in the horn.

If loss of a horn plug is a concern, just remember that once you are done pouring powder you have to do something with the plug so you might as well put it back in where it belongs. In 45 years of traditional ML shooting I have never lost a plug.