[Lewis Thomson (OP)]

Colan asks:

When I was a child, I would fill my water gun up and pump it to the maximum pump level and shoot off into the distance. Netwon’s 3rd law would then come into play and the gun would press backwards into my shoulder with some force. I would then do the same thing again, only this time I would stand about a meter from a wall and shoot directly at it. It felt as if the force on my shoulder was now much greater than when I had shot the water into the air. Was that just my head playing tricks on me, or was there another force at play?

What do you think?

[Bored chemist]

Was that just my head playing tricks on me,

Yes, unless you were really close to the wall.

[syhprum]

To be really pedantic there must be a tiny, tiny, tiny force  certainly nothing you could feel