Well, unlike the sabots for a tank shell which have to stretch between about 30 to 120mm to make up the gun barrel, this is only a 19mm weapon which will fire a saboted projectile of maybe 5-13mm diameter. The 20mm Mk149 APFSDS fires a 12.75mm penetrator. As such, the sabots will be very small, and very hard to find.
If you aren't averse to the toxic battlefield, you could make the sabots out of depleted uranium and try and cause them to ignite on impact
However, DU is obviously ludicrously heavy and trying to fire a DU projectile /and/ sabot would probably detract from performance. Plastic is nicely liked for its light weight, and it only has to survive travelling down the barrel. You should look at polythiophene [link] Sabots would be difficult to self-police, but a railgun will probably send them (scattering) a few hundred metres downrange, and be small enough to be easily lost.
If you aren't averse to the toxic battlefield, you could make the sabots out of depleted uranium and try and cause them to ignite on impact
However, DU is obviously ludicrously heavy and trying to fire a DU projectile /and/ sabot would probably detract from performance. Plastic is nicely liked for its light weight, and it only has to survive travelling down the barrel. You should look at polythiophene [link] Sabots would be difficult to self-police, but a railgun will probably send them (scattering) a few hundred metres downrange, and be small enough to be easily lost.