Having used an original Gibbs-Farquharson-Metford match rifle in Long Range matches for quite a few years, I thought that I would comment. A replacement for the missing foresight can probably be found or made; the lateral adjustment screw on these tend to become sloppy with use, and it would probably be a good idea anyway to fit an oversize fine-thread replacement.
Having experimented extensively with cast, lubricated bullets, as well as with a supply of original Metford swaged, paper-patched bullets - there was simply no comparison in performance; Metford's bullets were the only way to go.
I was astonished at the accuracy of Metford's calculated range tables, of which I had a set. Setting elevations exactly to his figures I usually found that my first sighter was very often on target, even out to 1,000 yards.
I had a problem forming the .461" Gibbs No. 1 cartridge cases at that time, but now such cases are available from Bertram.
Competing with an original rifle against modern-made rifles, even those which complied with the "spirit of the original" rule, was not at all easy, and would be frustrating for anybody determined to bring home trophies; however, I found it a very worthwhile experience. My rifle was equipped for both the back-position, and for head-to-target shooting. I experimented with both methods, but finally settled on the conventional head-to-target; I just could not get comfortable in the back-position. The reserve is a bit high, but these original long range match rifles are getting pretty few and far between, and hopefully this one will be preserved, and not cut up to be made into another sporting rifle! Jonathan Kirton