What short starter are you using? I use this one from T/C and can load and shoot 30 plus shots without a problem:
http://www.cabelas.com/product/Shoot...3Bcat104436180
And I also use this rod with a flip up handle to seat the bullet. Not much pressure required, but some bores are smaller:
http://www.cabelas.com/product/Shoot...3Bcat104436180