whenever I hear that "boast." Some of my rifles are indeed capable of really good accuracy. Typically I obtain that accuracy at 200 yards or so, after the bullet has gone to sleep and before wind becomes a factor, if on a calm day.
I am especially suspect of such a statement when it is attributed to a FAL or most any "shell shucker" semi automatic, but that doesn't mean it isn't true... I have obtained several sub minute groups from my PTR91, but I have also obtained groups not near so good.
Too, it takes someone with extensive experience to shoot any rifle that well, and the stars have to line up just right, IME.
Sorta like guys you meet from the military... everybody was a sniper, nobody was a cook, a truck driver, a clerk, a radioman or a mechanic. I take those claims with a grain of salt too.
I'm not about to call anybody a liar, however, unless their story is internally inconsistent. It is your obligation to tell the truth, and my choice whether to believe what you say.