Most of the above recommended products will work perfectly well......IF you proportion and mix properly. I suspect, no, I KNOW most users of epoxy or polyester products feel that proportioning the product precisely is unimportant, especially when it comes to catalysts. Most will grossly over use the catalyst because there is so little of it required they want to be sure they get enough. The results are early failure, excessive shrinkage, cracking or crumbling, leeching of catalyst causing damage to metals and wood. Unlike epoxies, the catalyst is not incorporated or fixed into the final product. It is free to migrate long after the product was mixed, and it oxidizes with age which are some pretty good reasons to use only the correct amount.
But epoxies are quite different than catalyzed resins. They must have the proper proportion of A and B components to cure properly to produce the design characteristics. Most good quality epoxies are tolerant of mix errors up to about 7%. Above that, you're into unknown territory. So mixing Devcon 10110 at anything other than 9 to 1 by weight or the correct volumes will produce a significantly poorer end product than one mixed correctly. Excess resin or hardener will not be used up and will serve to alter the cured product such as producing an unusually glossy surface (that is easily damaged with strong solvents), at the expense of strength and excessive shrinkage as the uncured component dries out with age. I use a gram scale to weigh batches. 20 grams is more than enough to bed an action.
As far as shrinkage goes, a good quality filled epoxy has virtually no shrinkage, again when mixed properly AND no diluents used to thin it out for application purposes. This is the primary reason to keep it tightly sealed and in a cool storage environment as it will dry out with age and become less manageable during use.
I hope this helps.
Good info, especially the part about using solvents with epoxies. They say, "Never say never", but I would recommend that shooters without a degree in chemistry never try to dilute an epoxy product. If you need a lower viscosity, buy a product with lower viscosity. Don't try to cook up your own home brew.
And for polyesters, I can't think of any reason someone would use it in the shooting sports unless you're building a gun case.
Those who are not familiar with the products we're talking about should know that polyester resin is the stuff inexpensive boats are made from. It is, perhaps surprisingly, not waterproof. Think of it as a bunch of long molecules sort of like spaghetti. Where these strands cross one another, they want to naturally bond to make a solid structure. The stuff you buy has an inhibitor mixed in to prevent this bonding while it's sitting on your garage shelf. The catalyst you add just before use simply cancels the inhibitor and the product cures to a solid form. The catalyst, usually methyl ethyl ketone peroxide (MEKP) is not a component in the final part. You can control the cure time with the amount of MEKP you use, the more you mix in, the faster the cure. But, like anything else, there are limits. A little more might be better but a whole lot more is likely to be a mistake. By the way, getting MEKP in your eye is a good way to go blind. Generally speaking you can thin polyester resin with styrene. Polyesters are cheap, easy to use, and not very strong. Polyester shrinks a lot too.
Epoxies, on the other hand are usually stronger and, no surprise here, more expensive. There are many types, but usually they're quite waterproof and don't shrink very much. They use an entirely different way of curing. Think of a 2 to 1 epoxy mix as baloney sandwiches; two slices of bread and one slice of baloney. Ten slices of bread and three slices of baloney doesn't make five sandwiches. That is to say, the ratio is critical. So be careful when weighing or measuring the part A and part B, often called the resin and the hardener. Be certain to use the exact ratio specified by the manufacturer. Caution: The ketones in most epoxies is pretty nasty stuff and prolonged exposure can lead to allergic reactions. Wear gloves and NEVER wash epoxy off your skin with acetone. It will strip the natural oil barrier from your hands, let the ketones in, and sooner or later your hands will look like raw hamburger. If you happen to be a sensitive individual, your entire body will look like raw hamburger. Use vinegar followed by soap and water if you get epoxy on your skin.
Of course, like most things in life, the chemistry of polyester and epoxy products is WAY more complicated than the info presented in the above paragraphs, but I hope it may be of some use to those who have never given much thought to how these products cure.
