This is a good thread to revisit once in a while.

A couple questions I keep thinking of are:

1. If you are going through the effort to build and regulate a double for your own personal use, why worry about using maximum loads? IMO, reduced loads are more fun anyway - think cowboy action shooting. Load well below the accepted max. and mark the barrels as such. Or load with BP which is fun too.

2. How does a drilling pass a visual inspection at a proofhouse if it is impossible to see if a gap exists between the barrel and the breechface? Particularly if the rifle (high pressure) barrel is on the bottom?