By the sounds of it now, due to temps being moderate, not high, a few leaking primers (soot around the primer idicates this) - some blown primers - .212" primer pocket obviously at least .001" per side oversize. All the ammo of that LOT # is suspect. Leaking and blown primers indicated TOO high pressure for THOSE cases. Thus, due to the conditions, one can only say that perhaps the brass is at fault - as previously thought - or the powder charge or powder itself is at fault. This does not happen often - but it can and does happen.

.001" over non-fired, is normal absolute max on the first firing only, thereafter no further expansion is allowed - I personally prefer to see NO expansion at the head or rim. This is the head and rim of the case - NOT the web.

Case head expansion is usually something measured before and after - at the same spot (pre-marked) on the case.

Known safe normal maximum web expansion should not be exceeded.

Normally, with a ctg. that factory ammo is available for, I fire factory ammo that gives descent velocity compared to specs and record the expansion at the web- all around the web and on all cases - ie: before and after firing. I record that measurement average, maximum and minimim. Whether it's even all the way around the brass, or only in one spot. With handloads, I do not exceed that number.

I would not be concerned about the colour at the case mouth.

Dealing with wildcats is another kettle of fish, entirely.