If it helps any, the cap for the Base division is now $1300, however, there is not very cost effective to purchase a rifle/scope combo specifically to stay in Base. You shoot the same course of fire and distances in the same amount of time. The only difference is you are hamstringing yourself with MSRP value and can't take advantage of sales, pro deals, or used equipment. There is a VERY small list of rifle/scope combos that keep one under even the $1300 cap, and for what, being on a different column on the Excel spreadsheet than 80% of the other shooters. My philosophy is Base is meant for shooting what you have, and Open is for buying what you want or can afford.
To answer your questions, the trigger and action are the same throughout the 457 line. The chambers are different, Match on any 457 denoted 'MTR' and Bentz on all of the others. Balance and weight play large role in NRL/PRS. The longer barrel with the weight up forward can be of benefit. I see a LOT of 457 MTR's at matches. With a YoDave trigger spring and a Area 419 Arca rail attached, they can keep up with anything out there...if the shooter does their part.
