I see that this old thread has restarted, so will add to it FWIW.
Seems that I'm not alone with the changing eyes. Ten yrs or so ago, I started shooting the BPCR out to 1000 yds and bought a Kowa TSN-821M with a 27X eye piece. And it was used for the CBA military matches as well. It worked just fine.
Up until a yr. ago or there abouts, life was good. Then strangely enough, when shooting at 200 with my Mauser, seeing the holes became almost impossible. I never could convince myself to spend the cash for a Kowa variable eye piece and then finding out that they are not available anymore for the 821-M even if I did want one, it was either quit shooting or buy another scope with a variably eye piece.
So, I ended up with a Konus 20x60-80 from Optics Planet. It was a relative inexpensive scope as scopes go but the optics and definition appear very good. At the CBA military Nationals we shot paper at three hundred yards on friday and Seeing 30 cal. holes was not a problem even with the rainy overcast sky.
RD