Reloading OEL

I have a question regarding OAL and hoping I can get some help. I have a 338 win mag Winchester sporter. I have measured the maximum OAL to be 3.499 using 225 grain Accubonds. I determined this by placing a bullet into a split necked case then inserting into the chamber and closing the bolt.
The magazine maximum OAL allowed I measured to be 3.400.

Reloading books have the min OAL at 3.340 .

Is this normal or do I have serious throat erosion?
If normal, at what end of the OAL spectrum would you start?