Mine did loosen up a bit and is now within reason. Estimated less than 50 shots. Its still snug and i dont use much oil in the receiver area.

Of course your results may vary. Its only my opinion that in MY Extreme based 50 it should be ok with a little use. At first in my GMB54 it was super tight and this one is tight in my 50cal.

In the GMB54 i had to really give the breach plug a good tightening before mine would close and its gotten better ever since. Now i can tighten it to what i "feel" is enough. I think you are partially correct too, it appears some of the resistance might be in the camming of the NFPJ adapter in the receiver which should get better with use.

Win209s are the longest, maybe Fed209As will fit yours better. Just a few thousands makes a difference.

I hope you get it worked out. Mine was a PITA at first too.