[MikelTackNailer]

...add a spin/rotation to the grenade. That would stabalize the round in flight and increase accuracy.

On a Reforger back in the 80's we had a Blazer go rolling down a huge hill sideways with a case of M203 grenades in the back. While the officers were measuring turds we just went and unloaded it - six rolls being nowhere near arming the damn things. Good times.

[Svartalfiar]

On a Reforger back in the 80's we had a Blazer go rolling down a huge hill sideways with a case of M203 grenades in the back. While the officers were measuring turds we just went and unloaded it - six rolls being nowhere near arming the damn things. Good times.

The 40mm grenades have a complicated fuse system where you need both the firing force to move a pin, plus the rotational force to arm the grenade. A vehicle rollover almost definitely doesn't have the setback force on the pin (~250fps muzzle velocity), and the rolling isn't enough centripetal force to rotate the rotor ball into position to arm it. (3600 rpm, and about 10-50ft depending on ammo model.)

Granted a freak accident could occur, but chances are crazy high that that would not cause any of the round to go off.

[Manly Warrior]

Old wives tales.

The number of revolutions is moot, it is the centripetal force generated by the rotational velocity that arms the fuze- think spring loaded pins with a locking mechanism, once the round is spun so fast, the pins slide outwards, lock and the fuzes FP is then free to strike the detonator upon impact.

37 rotations is a fairy tale. However, it indeed takes about 25 m worth of time/rotation to retract the safety pins and lock, so that is the “arming” distance”. Good thing, as the blast radius of the 40mm HE round ( used to be anyway) is 5 m, so you want the round to be friendlyy safe a bit downrange.

Specs on newer rounds may have changed since my time as a Grenadier.

Regarding putting a round through a window at 150m- even the old M203 with folding sights could get that done- if the gunner actually knew how to shoot- all of the fundamentals of marksmanship come to bear.