I realize you are South African and I'm an American, both of us suffer from limited shell choices for fine guns. The Brits have a lot of choices from Gamebore, Eley-Hawk, and Kent. A traditional cork or fiber wad opens the pattern up quite a bit. A modern wad cup tightens the pattern. It would be worth buying some british shells for your gun (2.5" is excellent and wholly sufficient, 2.75" is fine if you can find them with fibre / cork wads) I think you'd have great fun shooting sand grouse from your gun with a fibre wad, 1 oz, 2.5" load of say #8 shot.
We spend years accumulating a variety of shells over here so we have the ability to get the patterns we want without altering our nicer shotguns and drillings.
Another wonderful shell you'll want to find and will take some work: The brenneke slug is designed to pass through chokes without damage, up to full choke. They have fins on the slug and a cork wad attached to the back of the slug to seal the bore. They are shockingly accurate to 100 meters. Expensive and sold in packs of 5, made in Germany, you want to accumulate some of those for your wonderful gun too.
If you really want to kill things with authority, a couple very expensive boxes of Kent Tungsten shells do horrific destruction. #5s and #6s would kill things as large as the tiny-ten.