Pakistani 105mm APFSDS round
In 2001 Jane's reported that Pakistan, as well as having produced a 125mm round, had also developed a 105mm Armour Piercing Fin Stabilised Discarding Sabot DU round for the Pakistan Army's Chinese designed Type 59 tanks.
The gun on this tank appears to be a replica British L7 rifled gun, which was fitted to the first version of the US M1 Abrams tank (with the designation M68). A version of the British L64A1 tungsten based APFSDS round, built under licence, is also available for this tank. Presumably other rounds, such as high explosive, are also available.
The manufacturer of the 105mm round is not known for certain, but it may well be the Pakistani National Development Complex, manufacturer of the 125mm round.
Pakistan has also apparently supplied with 10,025 105mm M833 rounds by the US. It is possible that, rather than having developed and domestically produced a 105mm round, Pakistan simply uses this stock of M833 rounds, which were originally designed for the M68 gun.
In 1998 it was reported in the Pakistani press that large numbers of DU rounds had been imported from China. It may well be the case that this included 105mm rounds.
The photo shows a Chinese Type 59 tank. Exact version and gun calibre are unknown