Same problems here.. I went with the advice of one of our posters, went with a marbles front and the O.R.H. on the rear. This was on a SRH , in 454. Worked well for hunting situations , fast to acquire , easy to see. However , off the bench for bullseye work....didn't suit me... believe I tried too hard, couldn't get a good sight pic. The instructions even tell ya not to concentrate on the peep....just look through find the front post and shoot. Your eye will automatically center the front within the peep. I ended up putting the rear blade ( white outline ) back on using the marbles front ( green ). Use that now , works well for me.
regards , irold