It seems like the manufactures should have different lenghts on the ballistic tips. Have a question though, if I size a case and then put the slug in just barely enough to hold it in and chamber it in the gun the bullet should push in to the barrel lanns and if I were to set it in there another 3 thou. that should be good right??????????

Right, but the ogjive varies by as much as .025" from lot to lot, and as much as .010" within your box.

In addition, you want at least half a caliber of bullet shank in the case neck for obvious reasons. Some factory throats are too long for light bullets, if you want to seat into the lands.

.003" off the land is just too close. Variations in ogive length and in seating will likely end you up with a bullet into the lands when you least excpect it.

Back up at least .010".

I do ten as well.

Okay then I'll back off some more but that is correct on figuring out my headspace right?

Wrong.

Headspace is the amount of airspace between the bolt face and the rear of the cartrige case. It is adjusted by pushing the case shoulder back with a sizing die. You want between .005" and .010" and no more, else the casehead will fail prematurely.

But that is a Rough way of determining the distance to the lands for that particular bullet in that particular rifle. Often the Lands will grab the bullet and throw the results of your method off.
If you want to get better and easier measurements---go buy a Stoney Point Comparator gauge from Cabelas for about $23.

Or save the money and use a cleaning rod. Put a bullet in the chamber so it is against the lands. Use the eraser end of a pencil to hold it in. Run your cleaning rod down the barrel till it touches the bullet. Put a mark on the rod where the barrel ends. Some use a marker, but I use a razor blade. It gives a finer line and a more exact measurement. Load the bullet into a case, no powder or primer for safety reasons. Put the dummy cartridge in the chamber and close the bolt. Insert the rod again and make another mark. Now measure the dummy round and the distance between the marks on the rod with a caliper. Add the measurements and you get the Max COL that puts your bullet into the lands. Then just decide how far off the lands you want to be, subtract from that max length, and set your die.