What wavelength (green/red) unit were you using; how long to discharge the rounds and what was the ambient air temp approximately? Also, firearm spec and ferocity of recoil may help?
As mortuus (perhaps a very apt name on this occasion) suggests It does sound like a dead diode but the above may help to diagnose for certain.
Are you sure it isn't a dead battery? Even
just the battery bouncing around in there
can cause problems. The laser really
should be designed specifically for firearm
use. Also overheating is bad as others
have already said.
Well, I was switching the unit on and off. It was about 78 degreesF. I was using a 9mm +p handgun with blue 445nm laser. I finally was able to make awsome groups and the unit dimmed. I thought it was battery related. But nope. Then I thought it was a bad connection, and it all of a sudden came back to full power and thought I was good to go after fixing that. But now it is dim again.
I guess the unit was also getting blasted by the gas fireball as it was ahead of the barrel. Oops.
Yeah, the insulation around the battery may
have rubbed off and shorted it out. The
bouncing also causes intermittent contact,
which can send current spikes to the diode
and kill it. This is why laser gun sights
have either a separate battery pack
connected via cable and placed in the
shooter's pocket, or a special battery
compartment to keep them from moving around.