I was not sure where to post this, but I figured here was as good a place as any.

I made up a dummy round for my Sako 75 .375H&H to set max COL for a load with 210gn X bullets, only to find that it was too long to be axtracted...

Is this normal or is something going wrong here??

COUPLE of things,
first your load length is really limited by the COL allowed by the magazine size, unless you are only going to single load. People have been doing the long bullet bit for ARs they are long range shooting for a long time.

Did you see if it would stack in the magazine?
If not try it. My guess is it won't fit there either.

Second thing is if you REALLY want to have a round longer then the mag box, no big deal, once you fire it you are just ejecting an empty case, which should be no problem. Just can't fill the mag box with them.