Perhaps send a sample to Delbert ( Load Lab Home Page ) and he'll test it for you? However, what will the results really tell you? A representative sample breaks at x pounds of force. Does this then mean that the chain can be safely used to support x/5, x/7, x/10 (whatever safety factor you want to apply) pounds?
What I find most interesting about this is that two samples of a quick link failed at very different loads (2415# and 4850#). Which to me says that even if the non-rated hardware seems to be able to take the load, you can't trust the quality control. There may be a bad apple in the bunch.
It's not a matter of wanting to use it, it's a matter of wanting to remove. Without giving a location, it is in the pictures of bad rigging on a well known rigging company's site. I am familar with the location and it needs to go. I'm not sure that you really want a known breaking point because it could be turned around saying the weight on it is less than the breaking point. As noted above inconsistancy is better ammo than an actual number. The other problem is what it is attached to above. That's shakier than the chain.Careful with blanket statements. For example, remember, the most common chain used for batten trim chains, 1/4" proof coil G30, approved by OSHA for the use, IS NOT rated for "overhead lifting".
One of the problems with anything being used in a manner for which it is not intended, or pushing the limits, or working with "unknown" capacity, is that failure is highly unpredictable, both in initial strength and with sudden failure at a loading or force that worked before.
To do a meaningful "test" would require a meaningful number of "breaks" with several different sources of the twist-link chain we all lovingly call "Dog-Chain".
As for a test proving what the OP wants, "be careful what you wish for ". A test that shows your higher-ups intended use may not fail.......this time. What you really want, even in a small sample, is unpredictability. Highly different results between several samples.
What is the use someone wants to use the twist-link chain??