someone will probably suggest locktite but i would not do that, unless you plan on never maintaining the bolt again. i have never heard of that happening, make sure the oring on it is good so you can get a good tight twist on the allen key w/o damaging anything.
But there's no sense crying over every mistake
You just keep on trying 'til you run out of cake
And the science gets done and we make a neat gun
for the people who are still alive