Biggest problem for clay targets is that most Drillings have tight chokes, mod & full or tighter.

A 24" barrel Drilling by the way is called a Kurz-Drilling, (Kurz meaning short). A short barrel might make getting full velocity from the 7x65R a challenge, but there will be powders that can do it, if you experiment. If you use Hirtenberg 7x65R cases, beware that they have a small flash hole, so simply bore it out or loose your decapping pin.