The easiest and safest way to test the rifle is to do as RR mentioned...take a primed case (now powder, no lead) and attempt to fire the rifle with the lever in the "disengaged" position you mention. I own a pile of lever guns including 2 BLR's and mine do something similar to what you describe but will not fire in that position...as soon as the lever "drops" the rifle won't fire (on my rifles).