Does anyone know what screw 75 does ? - http://www.steyr-sportwaffen.at/medi...load_ET_EX.pdf

This came out of my pistol last night causing a loss of power and pellets lodging in the barrel.
Luckily we found it and put it back. The pistol seems to be working OK again.
It's quite a loose fit and I wondered what the screw is for - doesn't seem to do anything except plug the hole.
Perhaps I should use some loctite243 to stop it happening again.

SJ