New to reloading and I'm using a hornady OAL gauge and comparator.

My load is for 30-06, Nosler 180gr partitions, starting at 43grs IMR4064.

I measured my rifle using the OAL gauge 3 times and got 3.972" each time with the comparator. I subtracted 0.030" to get off the lands a little and came up with 3.942". If I subtract the comparator (1.007") that only gives me 2.935" for an OACL. That doesn't sound right when the Nosler manual says 3.340 is max OAL. Where did I screw up?