Yeah, I didn't think it'd be that much of a challenge for you guys, more like a bit of fun...! As for Nyles', I got about 4 on there, but I was too embarrased to post and say so!
IGI was indeed 2000, I found the image above hidden away in the install directory years later. I agree with your gameplay comments, I loved it (and still do, I play it from time to time) because it was the first ever game where they gave you an M16 that actually looked and sounded right - and was the first game I saw that had proper muzzle flash!
Yes, I'm easily pleased, but back then the only other thing half-decent was Soldier of Fortune, and the weapons in that were over-the-top and cartoony to the max...
At that time I was just starting to take more than a casual interest in firearms (hence not being able to name any of them back then), looking at it now it's funny to see just how commonplace they are, especially in movies..
Anyway, top work, mate, looks like you nailed pretty much all of it. Here's my responses:
3. Yeah, I did think of erasing the stencil but I thought, what the hell!
4. Gun of the future indeed, can't believe this still keeps popping up in games and movies even though it was never actually produced...
10. My apologies, the image is truncated. I reckon this is a Browning M2 50.cal, you can see the vent holes in the lopped-off barrel.
12. You got me there, I didn't notice the folding stock, I just had AK-47...
14. Yep, I just had M1014, you had to go one better! ; -)
21. Yep. This was the very last one I found, took me ages!
23. You're absolutely right. I had this wrong, the flat sheen on the barrel should've given it away. My bad!
26. I had M61 grenades, but I've no idea how you tell the difference.
28. USMC KA-BAR knife, was my view.
All the rest are spot on - and usually more detailed than what I had!