1) There are a number of advance reloading techniques. The one most popular alternative method to reload bullets is one in which makes ammo that only fits a specific gun and made so tightly to that guns bore diameter that accuracy is improved. The idea is to take fired cartridge cases from the gun and to only resize them to the point that the shoulder of the cases are pushed back a few thousandths of an inch, not to the industry standard amount that assure the cartridges will fit any gun of the same caliber. This technique is better than neck sizing only as it ever so slightly sizes the case to assure that they will always fit the gun, unlike the build up of tolerances that can make neck sized only cases eventually no longer fit the gun’s chamber.
A RCBS casing gage is used to measure the fired brass cases length from the reference point (on the shoulder) to the end of the case (the base). The sizing die is backed off the shell holder. The case is therefore sized sequentially shorter until it is about 0.002 inches shorter than the case gage measurement for the fired case. The sizing die is then locked down and the batch of cases processed.
2) Moving the bullet out to just short of touching the rifling in the bore of the barrel of a rifle assures the bullet gets started as straight and as close to the bore’s centerline as possible. The best accuracy is often achieved with this method, which we refer to as bullet seating.
But of course there are some disadvantages reloading bullets to this method. The bullet should NOT touch the rifling or it will stall too long initially in the powder burn allowing the pressure to build up beyond what is safe. The baseline loads should be used and working the load up, not to exceed the maximum listed in the manuals or at signs of excessive pressure, whichever occurs first. It should be noted that best accuracy rarely occurs at or close to maximum loads. The longer than standard cartridge may not fit into the gun magazine so keep that in mind if magazine operation is required.
How do you when there’s excessive pressure? You need to look at your spent primer and see if it as sharp edges. Sharp edges means that the pressure is high enough to plasticity deform the primer into the shape of its surroundings. Ideally you’ll want to see a soft primer edge.