Not a Boer rifle, but a Cape Govt rifle of the sort issued to Town Guards and blockhouse guards:
Holt's (UK) Fine Modern & Antique Guns - April 2026 : Sale A0426 Lot 705
A .577/450 (M/H) MARTINI-HENRY MARK II SERVICE RIFLE SIGNED ENFIELD, no visible serial number,
dated 1888, with 32 1/2in. sighted barrel, with Broad Arrow, 'WD', proof and inspection marks, plus 'sold-out-of-service' double arrow, bridge marked 'K.T / 6407' (being a King Williamstown arsenal stamp), receiver with crown over 'V.R / ENFIELD / 1888' / lock viewer's mark / 'II', receiver bridge with 'C/I\G' (Cape Government ownership mark) plus a another strike with a further reversed strike close above it (such marks were employed to indicate 'sold-out-of-service' by the Cape Government), full stock, left side of butt with Enfield roundel over 'II. / I', plus two 'sold-out-of-service' marks and 'XXI / M R C / 11', with sling swivels, clearing rod and modern sling