I thought I would bring this one back up again---seems like I have done that a couple of times recently!!

Since I am in the beginning stages of a build (and maybe two..!!), this subject holds more than a passing interest for me. I have read the entire thread----and something seems to be missing from the discussion.

I won't argue the advisibility of using shotgun actions or whether "proofing" is necessary. I think it is a great idea and so will proceed with that in mind. Here is what strikes me as odd: If you are considering a proof load and are wondering how to proceed, why not just develop a proof load?? Purchase a couple of boxes of new factory ammunition from different manufacturers. Take one or two rounds from each box and package them for shipment to a ballistics laboratory--these will be your "controls." Include with them some prospective proof loads of your own (maybe start with two rounds at "book max" then two at +4 percent, two at +6, two at +8, two at +10.....) or some similar arrangement. Have these rounds pressure tested by the lab. It will then be VERY easy to arrive at a proper "proof" load as required by the proof houses. No guessing, problem solved.

We know the parameters for proof (as published by the proof houses), we know what the manuals indicate as "max loads" and what that means (as evidenced by the manuals themselves), we know the design pressure parameters of the cartridges (as published by SAAMI or Birmingham or whoever..??), Soooo.....it seems a simple matter to load up a few rounds and have them pressure tested to determine a load that falls within the proof parameters of the proof houses. Yes..???

It goes without saying that you will need to record the load information of your test loads and mark them in a manner to identify them so the lab can record them properly on a data sheet. The only sticking point seems to be the availability of a ballistics laboratory. I know there are several (two or three..??) in the U.S. and all of the European proof houses can do this as well. I suspect there are labs "down under" as well and for that matter anywhere ammunition is developed and loaded.

Of course, I could be all wrong about this......