I had one of the early (shiny machined metal with sharp edges) models on a NF BR 12-42x for a short while. It worked... but for whatever reason, with these scopes, my eyes requires me to screw the scope eye piece (focus) almost all the way in to begin with, even with a fresh prescription. When I added the Bullzeye piece, I had to screw the focus in even further, and ultimately, there wasn't enough adjustment to get a perfectly clear image (for me). Strike one.
Then it also seemed to shorten up the eye relief considerably. I tried shooting with it anyway, thinking what a great boon this would be on top of the 42x I normally run that scope at all the time. Boom - WHACK! I thought to myself, "Dang, I didn't think I was crowding the stock that much." Strike two.
I made sure for the next shot to scootch back enough to be able to just barely be able to see any 'black' inside the scope tube. Boom - WHACK! This time... well lets just say the words coming forth probably would get me in trouble with Len here. I had a nice cut on my nose from that sharp machined edge on the eye piece, and thats even with an 18lb. .308 running 155's (not *that* much recoil). Strike three.
I removed the lense, cleaned the remaining blood off of it
called up the seller and explained what had happened. He was quite the gentleman about it, took it back no problem. From the sounds of things, I wasn't the only person with some reservations about the sharp metal edge. I noticed the subsequent generations got the rubber cover and a nice *chamfer* on that blasted eyepiece.
I'm kind of half-ways considering trying one on my NXS or on a Weaver T-series scope. I'd like to use one on the BRs but the eye focus issue is still there.