About two years ago I bought a Remington 700 sendero chambered in 300RUM. I have been reloading for this rifle almost since new. I have been loading mostly from manuals and loads found online. The first six months of owning this rifle was horrible as I didn't know where my loads were shooting from the constant flinching. After installing a vias brake, jewl trigger and a firing pin to match it, I have come to the conclusion that the only thing that my current loads are good for are is hearing reduction. My big question is where do you start to building an accurate load? Powder selection? Bullet seating? Powder charge? Also, I have a neck sizing only die from rcbs, but I was told that it could lead to pressure problems for a cartrige of this size, so I have been full length resizing. My current train of thought is to stick with the same load after better brass prep, and to follow the thread on here about best use of the berger vld as to the COAL. One last note, with my current load Im shooting 210gr Berger vld's out of remington brass filled with 93gr of Retumbo, and Winchester magnum primers setting it all off. I thank you in advance for any replies, and any advice is greatly appreciated.