Doing a double post, but:

I'm currently doing texture work for my machine gun, and the only way I found out to work with quake's palette limitation and making the texture look like quake is to use MS Paint, taking parts of the quake weapons' textures and working pixels by pixels.

Of course that's extremely tedious and eats a lot of time.
But since I have Photoshop CS6, is there a way to optimize texture work through it? 

We had a big discussion on suitable editors for quake textures about a week ago in mapping help, see the following posts for the bulk of it:

http://celephais.net/board/view_thread.php?id=4&start=15380&end=15429 

Daya: You can make 256 color palette in PS or GIMP, so you can convert your texture to color spectrum from this palette. You must copy Quake colors manually to PS Color Table and save it for later use.
Here take a look: http://graphicdesign.stackexchange.com/questions/654/convert-a-pattern-photo-to-a-given-palette 

I have one for GIMP somewhere, if someone interested... 

For your convienence I just uploaded the good old program Wally up to Quaketastic.
It is one of the good wad editors that were on the WadFather back in 2001 and can be very usefull if you're doing things with quake's texture.
It has a lot of feathers you can use, and is more specific than texmex.
My download confirms it is a dangerous program.

If it is more dangerous than the squad be aware,
so download on your own risk.

wally 

Wally was already at Quaketastic and is also available at Quaddicted.

https://www.quaddicted.com/files/tools/wally_155b.exe

http://quaketastic.com/files/tools/windows/wad_editors/Wally-155B.zip

I only knew because I went looking for it earlier this year. 

http://image.noelshack.com/fichiers/2015/39/1442965830-infantrygun.png

Keep in mind, this is the first time I'm doing actual texture work, and even after applying Quake's palette, it doesn't feel that "quake-y" enough.

Any tips on accomplishing that if that's not the case here? 

Make the barrel blue like the sng. 

Try using lower res textures(diff uv's) ATM it about q3 quality 

Tend to use mainly the darker half of the palette lines and don't have many bright bits. It's usually textures being too bright that make things look unquakey. 

http://image.noelshack.com/fichiers/2015/39/1443008160-infantrygun2.png 

But I think the checkerboard ork pattern on the muzzle is a bit odd. Maybe make it more transparent so you can see the metal texture underneath. That might not fix it though, since the UV cut to front is pretty harsh compared to the soft nature of the rest of the texture - created by the low res.

Maybe even remove / move it? 

Nah, it's something I wanted to make since day 1. Maybe doing transparency will fix it and a subtle halo surrounding the cylinder's face.

But then I've got another problem. When I export it as an .mdl file and check in QME to see if it has exported right, not only does it still have the g_nailgun texture (even though I seem to texture-assigned my texture), but the UV seems to have been reset, as I've seen while importing my bmp skin anyway. Anybody knows what's the problem here? And there doesn't seem to be parameters on the exporter either. 

I don't like the checkboard bit. Too bright for quake. 

http://image.noelshack.com/fichiers/2015/39/1443025682-infantrygun3.png

I'm asking again, has anyone had UV-reset related problems when exporting a model to .mdl ? 'Cause it's the only thing keeping my stuff away for being Quake compatible. 

I'm asking again, has anyone had UV-reset related problems when exporting a model to .mdl ? 'Cause it's the only thing keeping my stuff away for being Quake compatible.

What's your conversion process - which program do you make the models in, and what do you use to export it? It is possible to make quake models with nice UV maps with the correct process, e.g.
https://tomeofpreach.wordpress.com/2012/12/15/ogre/
However, Quake itself had very simple back-front UVs and lots of tools don't support anything more.

RE: v3 of the skin, it's improved a lot as you've taken the feedback on board. Have you tried overlaying scuffs and scratches onto the metal to make it a bit less "clean"? It's easy to go too far the other way with that stuff but I think it's worth a try, particularly on the browner metal bits. 

You mean it deletes your UVs?

I've had all sorts of problems, even it twisting the UVs round the model in a swirl. Really it just depends on what your tool chain is with these old formats and what tyou're rying to do. Not long ago it wasn't even possible to properly Uv a model. With some trickery in Noesis you can now get around the front back limitation, but I can't even remember what the method for that was. 

 

I'm using Blender 2.65 and using a Quake importer/exporter plug-in that is said to be "not even in alpha". I also have QuArk, but I only use it to convert quake 2 model files into .mdl files so I can import them into Blender. Maybe I can do something here related to my problem?

And if you're interested, here's the texture map of the Infantry Gun (or Nailbuster? I still hesitate between the two names) :
http://image.noelshack.com/fichiers/2015/39/1443030916-g-infglowblue.png 

It's looking good now from the screenies. The real test will be what it looks like in-game :} 

The best most fool proof way is to export to md3 and use preach's conversion tool. It is flawless. 

Yeah, try grabbing the MD3 exporter for Blender, and then use this "compiler"

https://tomeofpreach.wordpress.com/md3tomdl/

to make an mdl file. See if that's a bit more reliable - if it's not then it may be something that Blender does and we'd need to find a Blender expert. 

The error message is as follow:

http://pastebin.com/saMveW4p

And I downloaded the exporter from here:
http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Import-Export/MD3

It seems to have something about the normals, but I don't think that's the case. 

The function calc_normals_split was not present in Blender 2.65a, are you able to upgrade to 2.6.9 (which the MD3 plugin is rated for) or perhaps some more recent version? 

So I did just that (2.75), the md3 exporter worked fine, as well as Preach's tool, but when I open it up in QME, the model's all yellow and it has a shitload of nameless frames (even though the second time I tried that I made sure to put the timeline cursor at the very beginning).
I've seen in the InsideQC forums you have to make texture assignment, but I have NO IDEA how to do so. The post itself didn't help (and the noob-smashing tone definitively didn't help...), and even the Blender wiki itself doesn't tell you where the texture pannel is, or where the mapping tab is... https://www.blender.org/manual/render/blender_render/textures/mapping/uv/applying_image.html

It's so frustrating ;-;