Apologies if any of the following comes off as rude; I try and be as blunt as possible, because in my experience sugar-coating things helps nobody.
You guys have a start, but you're still a long ways off of anything that's going to look good ingame. I can see you're starting to learn for yourselves, which is definitely good, and people are willing to help - however some of the suggestions I've seen are not exactly what you should be shooting for and you guys could probably put my ranting to good use somehow. I've been modelling on-and-off for about five years now and while I'm actually quite terrible in practice, I spend a lot of time around friends who aren't and so I know the theory behind it. I use 3DSM v8, I'd imagine the other major programs have the same general features but I can't tell you where to find them, sorry.
What I'm seeing is a bit confusing. On the one hand, some of you seem to struggle with basic proportions but pull off all sorts of wild curves which would make me want to give up; on the other, some of you have perfectly-replicated weapons... except for massive smoothing errors which I honestly cannot work out the source of. I don't know how long you guys have been doing this, but you've clearly got at least some idea of what's going on.
I'll make some suggestions here to get you guys headed in the right direction. First of all, always work off of as many reference images as possible, and as accurate as reference as possible - avoid airsoft guns or movie props if you can help it, as they're usually close but not always 100% accurate (someone I know tried to model a G36 based on an Airsoft reference... as you can imagine, the magazine was entirely the wrong shape, but he didn't know any better). If you can, set up a side, top, and front view in the corresponding viewports; if this is impossible for whatever reason, try get a side at least and eyeball the other two as closely as you can. Never, ever try and model without refs - I have an intimate knowledge of a wide range of weapons and know exactly what they look like, but on the few occasions I've been stupid enough to try and eyeball everything, the proportions ended up horribly off.
Once your refs are set up, choose a good start point. Usually the receiver is the best place to begin a model, as everything else is attached to it; it's kind of like a natural workflow. Depending on the shape of whatever component you're modelling, there are a variety of ways you can do it, but in nearly every case the best way to make anything bar a cylinder is with plane modelling. For this, you'll mainly be using create plane-cut-extrude-edge extrude (you can get away with chamfers and bevels but I would seriously recommend avoiding them both). This also allows you to create complex shapes, holes, curves, whatever you like without using boolean (which is another thing to avoid until you're very much confident, because it makes a mess which is annoying and tedious to clean up) or primitives. Obviously you'll still be using n-gons for barrels, gas blocks, etc., but that's about all you'll need it for.
I'd go through and give detailed crit on each of the models posted here so far, but two things stop me from doing so - my internet is currently on the fritz and takes several minutes to load each one and I'm also a bit pressed for time at the moment. Depending on how we go I might do this later or I might not, but for now I'll leave you guys with
this video tutorial. It's not perfect, but it's probably one of the better things to start you off with plane modelling and as long as you don't forget what it demonstrates (like I routinely do

), your work should improve dramatically.
As a side note, I've been considering actually finishing a model lately and having recently got myself a beautiful 1944-made No.4 Mk.1, I'll probably model that... I might also give the No.4 (T) a shot, since that would simply entail adding the mounting pads to the receiver wall and then a No.32 scope and mount. I won't come in and try do everything else (and nor could I... I'm a horrific procrastinator) but I'd like to help you guys along wherever possible, so once my internet is squared away I'll be able to give you proper crit on your progress so you can improve it as you go.