Question: it is my understanding, it’s being said to seat the bullet to where the boatail is at or above the neck shoulder junction. I have always put the boat tail at or above the case, body and shoulder junction. I avoid compressed loads, and I don’t use up any powder case capacity.
If the bullet allows for this i.e. has enough bearing surface in the neck, what is the advantage to having it seated at the neck shoulder instead of the case, body and shoulder junction?
the real determining factor will be one of two things, how long your throat length is and how long of ammo your magazine system will accept.
i generally start load development with my custom rifles with the bullets seated at 0.010” off the lands and seldom need to play with seating depth at all to find a good 1/2 moa class accuracy load.
that said, i build the rifles so i know what the mag length will be before i start the barrel machining and cut the throats to use the bullet we want to from the start and fit into the mag box. If mag length is of no concern, ideally, seating the bullet to the base of the case neck, or slightly above this avoids any possible issues if your brass has a donut at the base of the neck. Some brass does, some does not. This donut is a thickened area of brass at this junction formed during the neck down process. It can cause some consistency issues in some rifles.
honestly, this issue has been over blown a bit. In rifles with very min spec chambers it can certainly be a real issue but in most rifles not much of a problem, more something experts like to talk about and make people worry about. Still it can cause issues in some situations when the bullet is seated deeper into the case.
seating bullets as you are is perfectly fine and actually preferred if that length ammo functions through your rifle. One must remember though that a long seated bullet is more easily moved out of alignment of the axis of the round then a shorter seated bullet. This is not because of the amount if grip the case has on the bullet but more then leverage action that is greater with a longer section of bullet outside the case compared to a round with a shorter amount of bullet hanging out of the case.
so its wise to be careful and smooth feeding long seated ammo out of mags and not running your rifle like your aditioning to be the next hot shot shooter over on snipershide.com……😳😊
in my testing, seating bullets long compared to seating bullets short really has little effect on a rounds ultimate performance level, AS LONG as the best powder is used for each application which most certainly will be different between a long and short seated ammunition. Thats a topic for another post though.