I sighted in both rifles at 100 yards so that they would be about 3" high, following Jack O'Connor's sighting recommendation in one of his articles. I've shot the Belgium (non-BOSS) rifle out to 400 yards on elk and it's a keeper. I've only shot the newer BOSS rifle out to 300 yards and it shoots well also.

I haven't really played around with the BOSS system to see if you can get that last 1/2" or so of accuracy by tuning it. With the BOSS unit on the rifle, I found it was too long for me (YMMV). If it was the only 338 I had, I would probably replace the BOSS unit with the threaded cap that comes with the rifle as well.

On a side note, the BOSS system is much louder for the shooter and especially for your buddy nearby. My buddy found the non-BOSS rifle tolerable but said the BOSS equipped rifle was just too loud to be anywhere near me when I shot it. I've heard that many guides don't like the BOSS equipped rifles for the same reason but haven't personally spoken with any guides about it. Like most of us on here, I tend to go the DIY route for hunting but, also like many of us on here, tend to hunt with a buddy.