Time and time again we get the question, is this load safe and the usual answer is based on something like start low and work up. However, primers deformation has been established as relative based on the type of primer, i.e. thickness of the envelope.

Now come the more difficult part. A proposal for a test bench to answer the above question. If you are worried about the barrel shank then mount a strain gage in the usual manner. 

However, usually the question is really about breech thrust and to simplify the test one should actually measure the stretch of the area stressed by the breechblock. 

One builds a simplistic falling block. An adequate breech block normal to the bore. To avoid having to make multiple frames start with a barrel thread too large and bush down for real test barrels. Make the frame symmetrical to the chamber so thrust is evenly distributed across the web. The web thickness is adjusted to accommodate a maximum thrust in the range of 10K lbs.  If one needs more sensitivity use active elements in two legs of the bridge.

Nothing is easy; one still needs a range of test barrels/chambers. 

Did I miss anything?

Comments and suggestions for modifications are invited.

The usual failure mode on single-shot rifles seems to be barrel failure rather than action failure.   Lotsa small-shank bbls out there to look out for.

CHRIS
RGChristensen