problem w/ this gun light set up?

I would be concerned with muzzle blast and unburnt powder more than anything.

Um... I'm not sure why you mounted it so far forward...? Will the clamp not fit around the magazine tube otherwise?

I had a light mounted for a while on my Saiga in a similar manner - it is the 16" barrel version and there wasn't enough room for the light between the end of the forestock and the muzzle. I actually rotated it around to the left side and against the front sight post to get a little more clearance.

I never fired it that way since I figured the muzzle blast would destroy the flashlight. I used it to check the yard for prowlers every morning for a few months (I never caught him/them - otherwise the flashlight would probably be toast )

Try this all the way back and ditch the coiled wire

www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=20919&
title

You will need this or similar to mount it!

www.vltor.com/vltor-mountables.html

Two problems

1. Like mentioned before. Unburnt powder is going to block the light out very quickly.

2. It might fall after a few shots. Give it a test fire. Since you're only holding on by about half an inch there's a good chance it will fall off during firing.

Another thing to think about is the purpose of having the light. Target identification? If you are going to use this gun for self defense you certainly don't want to add to its length. That will only interfere with your manuverability.

I carried a mossberg in Iraq. I used a light about 1/3 that size and no more
forward than the barrel/tube bracket.

Wow....bet you paid a lot for that.....