
There are certain custom weapons out there that don't use square texture formats. For example, they might be 2048x3072, as opposed to 2048x2048. This causes the textures to flip out and not format to their models properly in-game for me.
For background, I am playing on a potato, with Intel HD graphics (~3000?), at 640x400 resolution, textures on high, everything else low. Please don't mock my setup unless it's relevant to the error. Other custom weapons work just fine, all their textures fit correctly to their models. I haven't heard anyone else complain of errors like this.
I have several mods, both standalone custom and replacers. As far as I know, both BLT and BeardLib are up to date.
Does anyone know what could be causing this? Mod, game setting, computer is potato, or simply the game doesn't know how to handle the textures? Has anyone experienced a similar problem?

https://www.dropbox.com/sh/jcxmittp6vbby4d/AACxOD5g0Z_OdtlnSukOmIGna?dl=0 This should be a folder containing some small pictures detailing some of the messy textures. I'd have to re-download those mods to get images at a higher resolution.
The mods demonstrated are the AKU-94
https://modworkshop.net/mydownloads.php?action=view_down&did=17577
And the McMillan Tac-50
https://modworkshop.net/mydownloads.php?action=view_down&did=18573

It's possible Beardlib auto-updates messed them up, and now they just don't look right. You would need to reinstall them to confirm that though.
You could also try re-buying them in your inventory, maybe it'll help.
But if it's not the game, or the mods, then make sure your system isn't overheating. That causes weird visual bugs from time to time.

I don't know about system overheating, that could be a thing. However, it's so far only with the "non-square" textures, as confirmed by the author of those mods. Things like the foregrip on the AKU and the bipod on the Tac-50 are properly formatted and display correctly. No other weapons in my inventory suffer from this issue, even during the same session.
I have tried installing both mods repeatedly, as well as another with the issue, the result is the same.

I have managed to get two mods I had issues with previously to work by resizing their textures to a square format in paint.net. So far it seems that only the size of the textures was the issue.
Can you post a screenshot of what it looks like?