IF you can get them to shoot, Powerbelts are the best for fast reloading! Three things to try:

Different weights of Powerbelts, and/or different powder charges with the 295-grainers.

Take the plastic gascheck wads off and put them back on, the idea being to free them up a little so they come off the bullet faster. If the wad stays on too long, accuracy will be affected.

Different kinds of powders.