Laser ends really abruptly

What if it was a gamma-ray? Then it would be visible cause of the track of radiation it leaves in it´s trail.

Sorry, but charged and high-energy are not synonyms in physics. Photons do not carry charge.
And I suspect you are referring to pair production in the second part... but total momentum is conserved in either case, so there's really no way to 'see' the products of pair production even if that were to occur (and it being a laser, pair production probably can't happen for the same reason. Imagine you were traveling near the speed of light (relative to the laser's source) in the same direction as the laser. You would notice that any interaction would have a low total energy in that reference frame, so clearly pair production cannot occur).

Also, as has been said before, that don't seem like no photon beam to me.

Okay, bad writitng then. Also the gamma rays does leave some sort of trail, detectable with a camera capable of detecting gamma-radiation. I dunno the exact term but they do leave a trail of radiation.

I actually much prefer that it suddenly goes and stops.
It gives an aura of quick brutality.

[citation needed]

Fixed that for you.

Some links on gamma ray burst afterglow:
http://astronomy.swin.edu.au/cosmos/G/gamma ray burst afterglow
http://www.nature.com/nature/journal/v437/n7060/abs/nature04174.html
http://phys.org/news/2014-04-gamma-ray-afterglow-scientists.html

And some links about the work of detectors, that hopfully will in the future be able to detect the ray itself:
http://www.rotse.net/
http://www.rotse.net/summary/
http://www.umich.edu/~rotse/
http://mcdonaldobservatory.org/news/gallery/rotse-iiib-telescope(McDonalds have their own observatory?)

Gamma ray burst is a high energy particle shower NOT a laser... pure gamma laser is going to

1. Be invisible
2. Pass trought most of matter
3. F*** Electronicts, Entirely
4. Superheat / Radiate / Melt / Explode / Whatever everything that matters
5. Give cancer to you and your kids

Idk about 4. part, because this thing passes trought most of things, thats why Ultraviolet / X-ray laser is MUCH better