22 hornet reloading

For any that have experience and can help I'm curious about a few things. Initially why does everyone using reduced loads used cast bullets? Are reduced loads safe to use with regular jacketed bullets? I have found many people using reduced load recipes in their 22 hornet using blue dot and 45 grain bullets, but could a person use red dot? I have had good luck using starting loads of lil gun and pistol primers for light loads, but nothing near under 2,000 fps like people using blue dot claim is possible. Chime in if you have done any of this.