You are correct about the measurement. That tip of the bullet to the base is to just ensure it fits the mag and is SAAMI spec.
If you wish to improve the accuracy of this rifle and your reloading abilities get a OAL guage and bullet comparator. Hornady makes a unit that is easy to use.
You will need:
Hornday Lock- n - load OAL guage and bullet comparator
Hornady OAL modified case.
There are cheaper methods using a unprimed case with bullet inserted and pushed in to the chamber. Insert a rod through the muzzle. Mark the rod at the muzzle. Remove bullet. Insert empty case without bullet. Insert rod until touches flash inside the case. Mark the rod. This is now your mark to mark measurement for that bullet type. It is not super accurate but it is close. The reason it is not accurate is the fact it does not take into account the ogive to bullet tip differences in bullets of that lot.
FYI. You have to do this with every bullet type, brand, weight change. IMO it is worth it to have the guage. I have 7 calibers I use it for. I would still have it if I just used it for one.