Devcon Titanium is a very high quality product. it does have some quirks though. You get about 15 minutes of open clamp time with it. A hot garage in August probably isn't the best environment to bed a gun in with this stuff. The basement is your friend. . .I suggest a glass plate to mix on and keep it spread thin so it won't develop as much heat when it starts to cure on you. Have all your ducks in a row long before you start mixing as it's a wholly hell to clean out of a stock if something goes wrong.
It's abrasive as hell when cured.
Shrinkage, shear strength, shore hardness, resistance to chemicals, and compression strength are all quite good with Devcon Titanium.
If you use it, I suggest mixing by weight and not volume. The use of a digital scale makes this pretty easy.
Devcon sells a supplemental product for this stuff that will extend the pot life a little. I forget the name but its a rust red colored concoction. It will also thin the stuff out a little too.
I use this product for all my tactical rifles and a few other applications. This resin system is the only one I've seen that is rated on the rockwell C scale vs. the shore hardness scale (what's typical for rubbers/plastics) When fully cured it emulates 12L steel- the low 20's in Rockwell C.
Tough chit. It's also about 100 bucks a lb.
Here's a couple samples of how it can look: