I don't guess you could post a picture.
87499 = 1897
That is Whitworth Fluid Steel, good steel imported from England and used on some of their finer guns as Damascus was being phased out.
Number 7 indicates an AA grade. They were marketed towards competitive pigeon shooters, which agrees with the marking.
These are very rare (5 hammer guns, 238 hammerless) and extremely valuable. See description and pictures at: