If you're really concerned about bullet jump to rifling grooves...
Take a piece of unprimed empty brass that's been sized (even just neck sized is fine if that's what you're working off of). Put a bullet in it by hand... make it stick out long. You want the bullet to not just fall in the brass, but also to not have an "impossible" to move it kind of resistance.
Carefully and slowly chamber the round by hand so that it's in full battery (admittedly easier with a bolt action gun).
Carefully and slowly eject the round by hand (don't let it go flying off).
What should have happened: when chambered into full battery, the bullet should have been pushed against the barrel / rifling / chamber throat ... and then further pushed down into the case. You might even just barely see the rifling grooves marks on the bullet itself.
The cartridge you just cycled will be your absolute max length to seat
THESE PARTICULAR bullets at
IN THIS PARTICULAR GUN. As mentioned above, you'll actually wanna back that off by a couple thousands of an inch (ie: seat a little deeper) to avoid pressure spikes. If you switch bullets or gun, re-run the test if you're going for as little 'jump/run' as possible.
Too much 'run to the rifling grooves' will affect accuracy, resting on the rifling grooves and you'll have pressure problems most likely.
With the above said... the general rule of thumb is that seating deeper causes higher pressure, seating further out decreases pressure. This isn't
always the case, but it's a good rule of thumb. You'll note there are several of these 'general' rules of thumbs that aren't absolutes
.
Keep an eye out on your primers, how the gun behaves, and what the brass looks like afterwards.
Be safe (your gun, yourself, and the spent brass will let you know).... and if in doubt, back things off a bit.