arrow length. to cut or not to cut

[scout308]

hey guys im shooting carbon victory arrows from my grizzly bear bow 50# at 28" and i have a 28" draw. they are 400 spine and full length. i had a heck of a time paper tuning and have to use 275 grain field tips. the dude where i buy my gear told me to keep the arrows full lenght. my question is,is it important to cut your arrows to length? and of course why? i dont trust his advice much since he set me up with 125 grain tips originaly and told me how great they were. when i paper tested they left a four inch tear to the right. i have them shooting nice and straight but man the tips are huge     .also my balance is really close to the front of the arrow. can i even find a 275 grain broad head?