But not really...
Walk down a beach. Step in the sand. Circle around and walk back on the same footprints... you’ve stepped in the same places, so it’s the same, right? Nope. Experimental design proves it’s impossible - your footprints weren’t there the first time, and they were the second time.
We know (and many have proven many times empirically) that shooting causes wear AND that the multivariate system of a statistically valid group requires exceptionally high round counts to produce anything meaningful. So effectively, reaming the throat or rechambering the same barrel is a meaningless exercise - by the time you fired enough rounds to establish the baseline, you’ve changed the barrel sufficiently to have introduced a new independent variable which influences the results significantly.
Equally, the experimental basis proposed is flawed: the hypothesis contends the 223 wylde chamber is more reliably accurate than the 5.56 spec chamber, whereas the proposed design would only work to rethroat a 223 Rem chamber to 223 wylde.
And of course, the qualitative observation is not an individualized phenomenon. Nobody (with any sense) disagrees that given a properly developed load matched to each of the 3 chambers could have just as viable opportunity to come out on top if tested one by one by one. But on the whole, a macro scale, it’s readily observed that 223 wylde chambers are more prone to shoot better than 5.56 chambers. The evidence base for this is massive - many, many guys start out shooting 5.56 chambers in competition, but over generations, it was realized certain attributes started winning over others, and the losers deservedly fall out of favor. Nobody has done an exhaustive study because the scale and scope is too large - but remains a massive body of evidence in front of us which supports the hypothesis as valid.
If you’re the guy willing to buy a hundred barrels, design a statistically valid round count to perform the “same barrel test,” maybe chamber half for 223 wylde first then set back and reream to 5.56, and the other half to 5.56 then set back and reream to 223 wylde, and fire thousands of shots just to learn for yourself what competition shooters have already taught us, then by all means, spend that money... even simply buying 10-20 barrels of each chamber from the same maker will take thousands of rounds to prove out... for what? To learn that freebore length and diameter and bullet jump matter? To learn that tighter chambers shoot better than those looser? I’d rather see that money spent on cancer research, personally, or on children’s educational programs - at least then it would bring SOME value...