Would love to see pics.
Grey Box I think is about double the hardness of oak. It's a hopeless feeling when you start with a new or freshly sharpened chain and it doesn't seem to go anywhere fast, producing mini-chips at best and mostly dust. If I were into more of that sort of action, I think I'd get me some .404 bars and chain that might last a bit longer between sharpens. A while ago I was bucking a big old yellow box (first time I had encountered it) log with a 32" 3/8 bar/chain that wasn't coming close to being long enough but was all I had and all the saw could oil in that sort of extreme use scenario. First cut was like 'heck, I must have hit some dirt', so swap chain out, then, still on first cut but going nowhere fast it was 'my grinding sucks, this is the second chain on the same bucking cut that is crap', so I swapped to a new chain and still was going nowhere quickly and had confirmed there was no dirt to pick up and ruin chain.
It sure made for some good firewood though. I didn't have a mill at the time, darn it.
Here's a recent Saligna drop and chop job:
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