My old pre-81 BLR in .358 Win will shoot under a 1.5" group at 100 yards anytime. Most groups are about 1" if I stop at 3 shots. That goes for handloads and the 200 grain silvertip factory loads. I have a 1.5-5x Leupold on it with a HEAVY crosshair, and I am convinced I can shrink those groups with a different scope. The trigger is horrible on my rifle!
I think most folks can expect <1.5" groups from out of the box BLR's on a regular basis, despite the trigger. A friend has the newer BLR in .300 WSM, and gets the same accuracy as I do.
I did have a very old made in Belgium BLR (first year or 2 of BLR production)in .308 that did not shoot as well, but I did not handload at the time I owned it, and did not experiment with different factory rounds.
Browning really cornered the market with the BLR by chambering it in "non traditional" lever action/carbine rounds.
