IMHO....seating to the base of the neck is just a 'general' practise for re-loading. It really depends on what bullets you are re-loading. I don't care if it is an SSK, a bolt rifle semi-auto or whatever. Anyone that has re-loaded for a any time and is looking for accuracy will tell you that the distance to the rifling is more important....and this difference changes with EVERY different weight, design and bullet manufacturer. For instance...The difference in 'OGIVE' (the shape and length of the bullet from the 'tip to where the bullet measures .375') ...this varies extremely in a lot of bullets. Look at a Sierra softpoint next to a Nosler Balistic Tip. The Sierra is short and fat, the nose of the Nosler is long and skinny. The Sierra will contact the rifling before the Nosler will if loaded to the same overall length (OAL). So.....for accuracy, the long skinny bullet should be seated longer, the fat bullet should be seated shorter.
Most reloading manuals will tell you how to check for this with each different bullet. Nosler says to use a spent case that has not been resized, sqeeze the neck slighty...just enough so it will ligtly hold the bullet in place, leave the bullet seated long and color it with a felt marker. Now close the 'dummy' cartridge in the chamber, and then gently remove it. The bullet should be pushe into the nect to where the ogive begins to touch the rifling. (the lands). If the bullet gets stuck in the rifling and pulls out of the neck, tap it out with a cleaning rod and you should be able to see marks in the ink where the bullet was pushed into the neck. Some bench shooters will seat bullets touching the lands, but most people back off from this measurement about .005.
