I personally dont like PLA for these builds because i want to build a firearm that i feel will last a good amount of time. Just alot of work to build an Orca out of PLA for it to wear out super fast. At very least i would say PET-GF or PET-CF for the Orca build.
That being said, its all up to your limitations. What type of printer are you running? I run PET-CF on my Bambu x1c but i have full panda updated extruder and hot end and ruby tip nozzle, plus i have an insulated chamber and active heating that can reach 60c. I also dry my filament and always keep it in dry storage. If i print PA, PPA, or any nylon. I am also actively drying my filament while it prints. Ive taken big steps to be able to print some of these more advanced materials, so im not 100% sure of the long term success of prints in these materials without some of these. I definitely dont recommend printing any nylon without active heating and vigorously drying your material.
I dont really think chamber heating is needed for PET, i know a enclosed chamber will really help especially considering layer adhesion is super important for these prints. But im curious on your print setup and can help you come to a decision. You could always print some test PET parts, anneal them, and done some stress testing by throwing them on the ground lol. But worst case, use some high quality PLA-CF.
