I have just finished loadings changing the seating depth for 52grn projectiles in my 223Rem.

The best group sizes were at .010" out from the lands and 0.008" into the lands.

I've experienced the same situation or very close enough for other weight projectiles.

Is this just co-incidence or is there a pattern or what-ever?

It is what it is. Every rifle is different, but you may find that generally seating at a certain length away from the lands works for your subset of rifles. I've had good results seating to the cannelure of various bullets.

It's a crap shoot. I usually start with the bullets as close to the lands as possible without actually touching them.

Numerous articles have been published on this subject, and as with articles of this nature, they have appeared to have varying shades of credibility.

The most prevalent theory is that changing the seating depth slightly is akin to modifying the nodes of the barrel oscillations in such manner that the bullet exits the barrel at a consistent place in the oscillation cycle. IF there is some grain of truth in this theory, then it would stand to reason that there is more than one seating depth which would result in consistency, i.e., multiples of harmonics. Hence, your finding two distinctly different seating depths which exhibit similar and better accuracy compared to other seating depths.

The downside to tuning for accuracy with small increments in bullet seating depth is that you could burn up a barrel (and a wallet full of money) shooting enough samples to discover the "sweet spot". When you factor in doing something similar with powder charges, powder types, and even powder lots, plus types and brands of primers, your variables are so many that it would seem statistically impossible to tune for the most accurate load during the lifetime of a single barrel.

the only way i load with the bullet into the lands is if i'm shooting where i have a cleaning rod handy in case one gets stuck . Ejecting a live round that has the bullet in the lands and having the bullet stick is rather embarrassing when hunting

Steyrl, the above posts pretty well nail it.
Typically I start at magazine length, and tune OAL last, and only if needed for the reason mentioned by Stoney.

Thanks everyone for the replies. I knew I get good, informative answers.