where to seat the bullet

I've been reloading ammunition for quite a long time now but never gave much thought as to how deep I was seating the bullet unless the bullet offered a seating crimp guide line. I have reloaded for roughly 18 years and just loaded the bullets to a good looking depth, but have recently read an article within "Gun Loads" where a reloader talked about seating the bulllet within 0.015" of the rifling. Maybe I read about doing that so long ago but have now forgotten the details. I guess a sized case, without the primer, could be used to seat the bullet to a depth shy of the rifling by a certain amount (maybe 0.015"). Once the correct adjustment of the die, the lock rings could be secured for that reloading task. Maybe I should do that for all my reloading, but haven't. I do crimp for the Win 94 30-30 and most all cast bullets. I simply crimp in the crimping grove of the cast bullets and what looks good on the 30-30, even though I'm using cast on the 30-30 now. I would appreciate thoughts on whether I need to crimp more of my reloaded ammunition. Here is a list of my reloads and what I crimp now:

.30-06 leave non-crimped usually w/jacketed bullets -- may use cast soon
.30-.30 usually crimp and use cast now
.30 M1 Carbine usually non-crimped w/jacketed bullets
.41 Mag. usually crimped using cast mostly
,44 Mag. usually a crimp w/jacketed bullets - must use jackets

I have also heard from someone, whom it concerned, that some or all 9mm's must be crimped in a special way because the case is used for headspace or something.

you are crimping properly now.
for revoilvers you roll crimp to keep the bullet from moving forward.
and if they are heavy loads good neck tension is required also,if light target poppers you may not need to crimp.
for your semi auto pistols that headspace on the case mouth i.e. 9mm 45 acp
they take a taper crimp.
for your lever actions you roll crimp to keep the bullet from being pushed into the case when chambering and while it is in the tube under recoil.
your 30-carbine is taper crimped also.
30-06 don't need a crimp unless it is used in a semi auto.

now the seating depth thing.
for jacketed there is usually a sweet spot in there for the jump to the lands.
i seat a bullet out till it hits the lands you will see a scuff mark on the side of the bullet.
i then seat a few more going deeper a bit at a time till the scuff mark is gone.
the bolt will close easier too.
now i take a measurement on the ogive of the bullet and use this as a starting point.
i then seat all the ones i used to get to this point.
and make 5 more at about .005 [5 thousandths] deeper and make batches going to .0010 then .0015 then .0020 now one of these are probably going to shoot better then the others.
i then target in on that area if it is the .0020 i continue on seating deeper.

this is assuming you aren't using maximum loads for your rifle as by going deeper will raise pressures.
what i have found is that usually they like a longer jump or one closer to the throat.
and not one in between.
now for your cast bullets they will usually shoot better with the bullet touching/engraving on the lands,depending on your nose type.
hope this helps