Chief RID,
I've addressed this issue two different ways. I've used an O.A.L. gauge and dummy case to match your caliber -- both made by Stoney Point. The gauge is a hollow tube with a shaft inside. The end of the tube is threaded for attaching a dummy case, which in turn is hollow, allowing the shaft to push against the rear end of the bullet. You insert the dummy case with bullet (it's very loose) attached to the gauge rod in the chamber. Once the case is chambered, then push the rod forward, which in turn pushes the loose bullet up against the lands. You then use the set screw on the gauge to set the rod in place and remove the complete apparatus. You then measure the case/bullet lenght and backoff the appropriate amount for seating your bullet. The literature I've read seems to vary about the amount to back-off, ranging from .003 to .020. I back-off .005 and it has worked well for my .223 shooting. By the way, the gauge is approximately ฮ and the dummy case ŭ.
The other process I've used is much cruder. I simply seated a bullet in an empty/non-primed case, leaving the bullet obviously too long to allow chambering (closing the bolt). I keep experimenting with the seating depth until I'm able to close the bolt -- giving me the maximum length.
Apologize for the poor description, but hope it helps a little.