Thank you for the replies.
Tim, as this horn is not mine, I can not say, but Mr. Pease says this is an ink horn, so unlikely to be threaded.
Mr. Pease,
Thank you for the information.
The one in the opening post came with the usual grey dust of black powder in it, but that could have been from any time in its life.
The suspension rings would infer use of something to be carried on the person, and as there were no long-hunters in the UK, a very positive nod still goes (in my mind) to gunpowder, as the measure is the same as on the standard Queene Anne types. (salt, sugar etc. not carried on the person),and as most salt was somewhat damp in the pre-iodized days, an open salt dish was used, rather than something with a narrow neck or spout.
Mr. J Pease,
I'd very much appreciate seeing your examples of the type in the O-P.
Dick,
I see these 'normal' Queen Anne occasionally at very reasonable cost, and will keep my eyes peeled for something for you.
A pal in the UK can ship for me.