I am getting into reloading and would like to know is it better to seal the bullet to an OAL or ogive length and why? Is it necessary to sort the bullets? Primary use will be for shooting holes in paper and varmint shooing.
First, and most important, if you don't develope the load with the bullet touching the lands, you don't want the bullet to ever touch the lands. This is becuause having the bullet touch the lands increases peak pressure by something between 6,500 and 7,500 psi, or more. That means backing off the lands enough so that the variation in bullet shape, between bullets intended to be the same, won't cause the ogive to touch the lands. Ever.
I've never seem as much as .020" variation in base to ogive measurement so I generally seat loads to put the ogive on a "nominal" bullet 0.020" off the lands. I generally measure 20 or 30 bullets from a new box, get an average, then look for an "average bullet", use that to adjust the seating die so the ogive of the average bullet will be about 0.020" off the lands.
Second, folks who load for a bullet "just touching" are generally kidding themselves. There may be special circumstances but I've never seen a lot of bullets that could be reliabily seated to "just" touch the lands. Seating to just touch will result in some being jammed, some not touching at all. The statistics on bullet geometry don't work for loading just touching.
Third, jammed into the lands is the most repeatable but not the most desirable on anything but a target rifle. It is quite common to unload a hunting rifle not having fired a shot. Bullets jammed into the lands can stick there resulting in the bullet being pulled dumping the powder charge into the action when the round is unloaded. Having a powder charge d umped into the action is "not" a feature.
Most rifles will shoot quite well, better than most shooters, with the bullets seated about 0.020" off the lands if the magazine length permits it. That's where I start.
I will be trying some Berger VLD hunting bullets this summer for the first time. I read their directions on how far off the lands to seat and will follow them.
Finally, I've tried about every tool out there for measuring chambers to decide how to seat the bullet for that chamber. So far the best tool I've found is the Sinclair tool that is a piece of precision ground rod with two sliding collars on it. It gives me the most repeatable measurements.