I can confirm that the original post is correct after I attended a brief recently at Lossimouth given by the Range Safety Officer at Tain who did indeed indicate the Army would be using D703 on the occasional weekend for weaponry training. I guess it will give the same problems as it used to do in days gone by when the range was often notamed as active on occasional weekends for the demolition of Unexploded ordnance. The big problem at weekends is that there is no one there to contact to give you an entry clearance into the range to allow access to Dornoch airstrip which indeed does lie within D703.
I think the solution should be simple by modifying the area of D703 for ground gunnery only.
Tain is close to my heart......I started my ATC career there 42 years ago. Checkout the link below in which the operator of Dornoch gives information about access to the airstrip.
Mid America (UK) Ltd | Dornoch Airfield Information