whitecap,
If it is a D.I.S.C. Extreme, it will use the red Full Plastic Jackets. You can also get a Non-Full Plastic Jacket conversion for it as well.
The older original D.I.S.C. Rifles used the orange primer carriers.
Your breech plug should have what looks like a big nipple on it that the Full Plastic Jacket goes over. You just need to put 209 primers in the jackets, then load them into the bolt, then move the bolt forward and down to prime. The bolt also removes the FPJ from the breech plug whey you lift and pull it rearward.
Here is what it would look like primed in your rifle.
The conversion would look like this.