Pull the jaw
Tooth replacement and wear is the most reliable field method for aging deer. Pull and label the jawbone from every deer harvested on the property, doe or buck. Photograph it next to the harvest record.
Weigh consistently
Record weight the same way every time: field-dressed or live-estimated, not a mix of both. Rising weights at the same age class are one of the clearest signs that your food and habitat work is paying off.