Not being picky, but being from the humid and often soaking wet South, I'm of the mindset that the objective of composite fiber stocks has always been to migrate away from wood which (unless it has been chemically stabilized) will always be subject to varying degrees of water absorption. Especially in the area where you have a recoil pad or buttplate, it can cause some swelling or flex of your outer layer of composite. This can result in the edge fit changing or worse your finish paint cracking followed by peeling.
Push come to shove, if you're not comfortable with mixing catalyst/hardener with glass, epoxy, or related resins, I hold-heartedly recommend Alves Apoxie Sculpt
https://avesstudio.com/shop/apoxie-sculpt/ This is a putty/clay type epoxy that is easy to mix and has a good 45-min working time. I use it for stock building, repair, and reinforcement including bedding. It drills and finishes better than MarineTex and other traditional epoxies and is just as hard and strong when cured. Not saying it's a replacement because as clay/putty consistency, it does not flow and fill voids as do the more liquid pastes; but I do think once you try it for stock repairs where you can't get liquids or pastes to stay in place, you'll find it invaluable. (PS. I've tried various colors but seem to get my best results with the NEUTRAL color.)
I believe there is usually more than a single way to accomplish an objective and my advice should be treated as an alternative not necessarily the best solution for you and how you do things. As always, YMMV.
