I've had them. Two symptoms, sometimes just one in a dream, but often both.

1. Trigger weighs like 40lbs. I have to use both my left and right trigger fingers together to make the gun fire.

2. Bullets seem to have no effect on the aggressor, and I run out of ammo before stopping them.

I'm like 0 for 40 on dream SD shootings. The two above problems always happen, and I wake up every time before stopping the bad guy or him stopping me