Going back to the PIAT, my dad, who was a tank driver, was taught about them during his training and said it was quite impressive, although I don’t know if he fired one. However he had nothing good to say about the PIAT’s predecessor, the Boys 0.55” Anti-Tank Rifle. He said he fired one once and that was quite enough!
Despite its recoil slide and rubber-cushioned buttpad, the recoil of the weapon (along with noise and muzzle blast) was said to be painful, frequently causing neck strains and bruised shoulders. Consequently, the Boys was almost never fired as a free weapon (that is, not affixed to a support) except in emergencies.
https://en.m.wikipedia.org/wiki/Boys_anti-tank_rifle
I looked up the muzzle energy of the bullet. Depending which specific round was fired, it was about five to six times the muzzle energy of a 0.303 bullet! No wonder the recoil was hard to manage.