I have used quite a few different products over the years; some specifically made for firearms, some not. My favorite for most use is the original Acraglas. It's a bit more difficult to use and a little bit quick in warm weather but it's hard, bonds well, and is impervious to almost any solvent. The Devcon products, Acraglas gel, J-B, and many others, will degrade if in contact with Hoppes#9. That's not a good trait in a material used on a rifle!
I also prefer the Acraglas to cast glass pillars. I will occasionally use Acraglas as a foundation bed then bed over it with Devcon. I do this because the Devcon will usually give a good final fit more easily than the Acraglas.
In using the Acraglas, I always add lots of fibreglass floc to thicken the mix. GD
