The particle, embeds and pushes the softer bearing over-lay out into a circle, then the oil is displaced from the high spot causing the journal to wipe the bearing in the high spot. That's what I see from the picture.
If there is contamination, the mains will flush the oil directly into the rod, main bearing has groove on upper half and ACL bearings will have lead-in groove on lower half.

look at how shiny it is... that looks more like very very high oil temps and a very weak film. the dots may be contamination but there are no striations from them so they were smaller than the clearences...

i think this is fractionally big clearences and 260 - 270 degree oil.

is there anything in the filter ?

Yes the main show the same thing.

Bearing clearance rod .00275 main .003

I have use merc oil filter # 35-16595Q for the 2 first oil change

and the merc # 35-881126K01 for the last oil change this season.

I have break in the engine with merc 25/40 and flush after 10h.

Refilling with merc 25/40 with ac delco suplement flush after 30h.

Swith with Royal Purple 20/50 xpr oil after 40h of break in

I can tell you that Royal Purple will never see another dime out of me . Expensive snake oil imo

What do you mean flush? Are you diluting your oil with an additive?

Flush ( change oil )

for additive i will give the parts # tomorow.
I think it is an additive with extra zinc for break in.

It still looks to me as contamination. Rod bearing clearance is not excessive, Royal Purple? I can not comment on it being bad or good. I do not see a shinny, rubbed area on bearing, but Iam not holding it in my hand. I am trying to understand all of this engine oil for break-in, I run 20w50 on the dyno for break-in, clean filter, than make my pulls after oil temp reaches 180-200 degrees. Will dump oil and refill after testing than install, new filter and oil after 10 hrs. 9 times out of 10,you could reuse bearings at fresh-up if engines are taken care of, but they are replaced as part of the rebuild.

Before to looking at the worng place i have tear down the engine due to a melting piston by pre ignition on cylinder # 6.
I can not belive is that thing have make contamination in the oil, If anything happen the oil should be filtered before got the main and rod bearing.

I dont think that is the piston aluminum particule got into oil and make this.

What did you think?

What about cavitation? Maybe it can look like this??

Did you save the oil that was in this engine? If so you could have it analyzed, that would tell you a lot about what was going on inside.

Scott