Is this in Hardcore v1.8 as well as Nightmare then?
If so I guess the issue must have started with an edit I made and carried over. I'll investigate it a little more and see if I can figure it out (FWIW in pj's updated Regular we are working on the problem does not manifest itself... peculiar)
I think it not unlocking for free was an intended decision by me (I would really rather NO weapons unlocked for free tbh). The intended reasoning was Longinus gave you THAT gun for free, but unlimited resupplies would require another more generous "donation" from Ajay's wallet. (I also kind of ignored Longinus speech about free weapons from radio towers for obvious reasons).
Thoughts on this (and free weapons in general)?
And all this science, I don't understand... It's just my job, five days a week
Don't know what's "pj's updated Regular" - it appears however to be a WIP.
Weapons availability - in general:
It all depends on what is the goal of any given mod, and what the modder wishes to balance. That being said, and depending on access to the original code within the game, here are two thoughts:
You pick up a weapon; it's yours; you found it!! However it must be taken back to a vendor/safe house in order to apply attachments; no pick up and drop simply to have it available later.
You pick up a weapon and regardless of what you do with it - if it was previously available for purchase, its now yours free for adding attachments; if it wasn't previously available for purchase, it is now (available for purchase). This would mean if you early in the game went out and got a more "advanced" weapon (say, the Z93), you can have it, but it ain't free if you decide not to keep it once found.
Generally speaking, cash isn't a problem in any version of the mods I've used, so buying a weapon as a only option still works - it just might take a bit longer to collect enough for a specific weapon,