7,62mm and 30 cal Frangible cartridges

My photo shows a 7,62mm Frangible cartridge head stamped FA 63 next to the 30 cal frangible M22 cartridge of WW2. The M22 was used to train aircraft gunners during WW2 by shooting at a special modified P-63 fighter. The weapon used was a special modified Browning AN M2 machine gun.

My question, why was the 7,62mm Frangible cartridge developed ? it fired a 108 gr bakelite and powered lead bullet at 1320 fps. It was not capable of semi or full auto fire in the 7,62mm weapons unless they had special modificationsAttachment 101497Attachment 101498

There were a couple of suggestions, one being close quarter battle training. Don't know about that...

The other came for dealing with hostage rescue such as the embassy rescues that took place. They could deal with the bad guys and not have over penetration after the fact by standard ammo...is that the reason you speak of?

I always heard aerial training. The frangible ammo would make dents to show hits on an aerial “drone” without doing major damage.

I believe the 7,62mm M160 was developed as a training cartridge, as to the weapon or weapons intended to be modified I do not have any idea ?

I have a few special purpose 7,62mm NATO cartridges that were found over the years, nothing really rare but still interesting;

My photo left to right:

1) 7,62mm M160 frangible 2) early red tracer for helicopter m/g 3)Japanese low recoil purple tip headstamp AO W63 4) Green tip duplex 5) white tip low recoil using a single 90 gr bullet from the green tip duplex FA 66 headstampAttachment 101516

US Manual TM 43-0001-27 June 1981 says the 7.62 frangible was "designed for firing single shots in the machine gun for gunnery practice."
Use MG 7.62mm M219 and M240