Not lesson #1 for me. I have run all types of small arms weapons ranges from basic orientation/qualifications both as Officer In Charge, as well as Range Safety Officer. This includes, pistol, and M16, as well as all full auto machine guns, (individual and crew served), as well as grenade launcher and Law Rocket. Literally hundreds of ranges on many different bases, many different types of range, dismounted, mounted, including combined mounted/dismounted simultaneous live fire assault ranges with carriers and/or jeep firing crew served machine gun over the heads of dismounted troops, firing M16. That range is a real ass clincher for an OIC or Safety Officer. My safety record is impeccable. Naturally, as an Armor Officer, I have OIC'd all tank ranges through Tank Table VIII, as well as Mortar Ranges, as I was MPOC qualified, that being my first Officer assignment in Armored Cav, and I have been Range Safety Officer over Battallion level Artillery fire and qual.
I have seen far more bizarre bullshit on civilian ranges, where simply firing on the same firing line with many civilians of a variety of different skill and experience level and range operated in a much less controlled manner. Nothing like observing first time automatic weapons fire, shooting at dynamite on a berm, barely outside the blast radius of the target explosive, with little range discipline in place by the ones running the range. Range operator was mostly tied up, selling ammo to the automatic fire nutballs. That was a range I left, quickly, without firing a single round, though it was a friend running the range, that invited me, and he was making money hand over fist on the ammo sales.