I haven't used ORGM in a long while, but I can link a wikipedia page of weapons that I'd like to see in this mod.

(Reminder, I don't remember what weapons are and aren't in the standard ORGM, so the list more than likely has weapons that are already in the original mod.)
The guns I'm listing are from the 20th century, *I think* most are from the World War 2 Era, which I understand the mod focuses on the 1980s-2020s, but I thought it'd be interesting to mention.

https://en.wikipedia.org/wiki/List_of_20th-century_weapons

I'm pretty sure there's quite a few guns in here that are already in ORGM, but may fit in to ORGM for 'older era weapons', but again, I understand this mod focuses on the 1980s-2020s, so I'm not gonna act like I'll force anyone into adding them in.

Not all of the guns in the wikipedia page are World War 2, some are (I think) around the 1970s-1990s, so that was a reason I mentioned it as well (edited after I saw the WW2-related comment and answer)

Will definitely be using that for when ORGM hits B41 and Fenris turns base ORGM into a more split addon base with a core framework mod where you just pick and choose what you want. No promises on adding this in the immediate future but I will be looking at this if I make a WW2 era addon pack with B41's full release.

Add russian gun VSS Vintorez it,s be interesting to see.Low Weight,silent shot, but just 10 bullets magazine.

Honey Badger, AKS74U, Scar H

matchlocks wheellocks flintlocks for pistols muskets and rifles.

I second the AKS74U,and add more Russian guns,such as AN94,AS VAL,PKM,RPK,RPK74,VSS,SVD,and a rather ridiculous request,a KSVK (some weapons have new calibers,if you need help implementing them, message me)

As for European guns,we have the SCAR-H,SCAR-L,VP70,HK 416,SCAR SSR,FN FAP,FN MAG(also known as m240),MG36,MG4,G36,G36C,MG42(far fetched but fun),FAMAS,G3A3(Unsure if it's already in orgm),MG3. There's many more,I'm not pressuring you or anything, just spitting out ideas with easier(as in already included caliber) guns to implement,I can even try to help you if you want me to.....

I'm thinking of some guns that aren't really seen in video games, but would match or closely the time period of the game well. Of course most of these I've listed have different variations and calibers, so that is up to y'all as to what exact variant and caliber to choose. Also these are all suggestions, I don't want y'all feeling like you gotta add these lol:

Pistols:

Detonics Combat Master
FN Forty Nine
Ruger P Series (P89, P94, P94, etc.)
Smith & Wesson 3rd Gens (5905, 3913, 4006, etc.)
Smith & Wesson Sigma
Star Firestar M43
Walther P99

Revolvers:

Colt Trooper Mk. V
Colt Diamondback
Colt Detective Special
Ruger Speed-Six
Ruger SP101
Smith & Wesson 686
Taurus 669

Rifles:

Browning BAR (Hunting Rifle)
Harrington & Richardson Handi-Rifle
Ruger Model 96
Ruger Police Carbine
Ruger Deerstalker
Savage Model 99
Savage Model 110
Winchester Model 88
Winchester Model 100

Shotguns:

Browning Auto-5
Savage Model 212
Stevens Model 520
Stoeger Uplander
Winchester Model 1200 / 1300
Winchester Model 1400

I know I put mainly civilian / hunting guns on here, but I did that because I thought they matched the 1990's Kentucky setting well

I'm going to suggest some very unique pistols which have unique design advantages and are most unlike any other guns you may have heard of.

Pistols:
Altor Corp 380 - a micro single shot pistol, super light, very easy to master
https://www.thefirearmblog.com/blog/2019/11/15/altor-single-shot-pistol/

S333 Thunderstruck - a unique 8 shot double barrel .22 Win Magnum revolver that fires 2 shots per trigger pull, light weight revolver
https://www.thetruthaboutguns.com/gun-review-standard-manufacturing-s333-thunderstruck-double-barrel-revolver/

Maxim 9 - Often called the "World's First Integrally Slienced 9mm Pistol", this pistol accepts Glock 17-18 magazines, fully supressed
https://www.eaglegunrangetx.com/shooting-review-the-silencerco-maxim-9/

Micro Roni (Glock Carbine Conversion Kit) - a unique attachment Compatible with all Glocks, attaching a glock to this, would allows considerably faster reload, Expanded Range, Handling, Accuracy and greatly reduced recoil. But it would be very rare of course.
https://www.thefirearmblog.com/blog/2018/02/08/can-shoulder-micro-roni-stabilizer/