In a double, where two constrictions are available, improved cylinder and modified are a good pairing, especially in fixed-choke guns. If screw-in chokes are an option, try a more forgiving match, like skeet and light modified. Shoot the more open barrel first on the covey rise, then the tighter barrel as the birds make their escape.
The CD and DVD have a single track of data in the form of a spiral, which starts as the center going outwards. The data is stored on the bumps or pits which are then read by the CD/DVD layer. The bumps/pits on a DVD are much smaller than on CD, allowing the DVD to store more data.
However, a blue ray reader can read or write on any of the types of discs and a DVD reader or writer can read or write on either CD or DVD. CDs, DVDs and BluRay discs all work in similar ways. The primary difference is the data density on each disc. CD is the lowest density. A DVD can store several times the amount of data on the same surface area and BluRay will store several time the amount of a DVD.