I just bought a Remington Sendero in 300 RUM. I am curious to know if its possible to open up the magazine to allow for a longer COAL. Is the issue in the action were the bullet is ejected or is it the size of the magazine? My brother in-law built a custom 300 rum using a Defiance action. His action is opened up to allow the bullet to be seated deeper into the chamber getting a more accurate load. This also makes me ponder the thought of building a new rifle for the new 7mm 195 grain Berger bullet. What brass is best suited for this round. I like the idea of 7mm STW or 7MM LR developed by Gun works. Does any body have experience modifying a stock gun to be more user friendly with reloading?