J.K. Hawken Rifle Kit — Step 1: Fitting Standing Breech to Stock
Video for this step: https://kiblerslongrifles.com/v/hawken-1
The standing breech is designed to be 100% inlet and should require no additional work to fit it to the stock. The stock could slightly change dimensions with changes in environment (humidity), so there is a slight possibility some fitting could be required. If so, follow the Notes on Fitting Parts to Stock above.
It is a good idea to check barrel-to-wood contact at the breech location with transfer color. Very little, if any, wood will need to be removed. It is very important that the breech position not change by any appreciable amount. Shaving a few thousandths to adjust the breech fit will not cause problems, but excessive wood removal will. If in doubt, leave the breech face alone.