Good observations. In addition, auto-mortar has a reduced no-sight penalty of 0.75, but this is a bit special weapon.
I took a peek at the other dropoffs in the rulesets. There are dozens of weapons with non-default dropoff. For reference, here's a somewhat summarized general list:
- mortars have 25
- sawed-off has 11
- typical shotguns have 6
- human sonic shotgun 5 (the power also reduces based on range)
- caws, db shotgun and thrasher shotgun have 4
- most or all pistols have 3
- many sniper rifles have 3
- dart rifles 3 and pistols, ads 4
- miniguns vary between 1 and 3 (HWP's often have 1)
- oicw has 1 (I wonder if this is intentional, it could be?)
- magma pulse lmg has 1 (I wonder if this is a mistake?)
Your observation on the the spread of CAWS shots is true. The default value for shotgunChoke is 100. The smaller value means wider spread. There are a number of shotguns which are more inaccurate than the default choke. Stay away from these if you can:
- small shotgun has 50
- ks23 has 60
- pump action and uac shotgun have 70
- smart shotgun has 85 (a bit strange as this should be one of the most advanced shotguns?)
I have had exactly the same observation wrt CAWS as you have. Especially with high accuracy, it can be quite accurate and deadly against less armored foes even with 20+ squares. A good weapon for example for environmental alert missions and Black Lotus HQ. Major bonus is that it can also take stun pellets and reloading them is fast.
In the very, very early game, researching non-standard weapons and the basic shotgun is an excellent upgrade over starting shotties because this gives you a significant shotgun choke improvement. A second surprisingly good upgrade is double-barrel shotgun, which has the same range characteristics as CAWS ie. extremely good long-range accuracy in capable hands. Especially useful in environmental alerts and against zombies.
As for my own favourites, here are the ones I have grown accustomed to using in the early part of my ~dozen SH/IM campaigns:
- .308 cal sniper rifles is the go-to weapon in 1997 and at least first half of 1998. BRV bonus to accuracy is excellent once your agents start improving a bit. Already usable with 80+ accuracy. Once you have decent bravery and firing accuracy, you can get 100%+ snap shots with this sniper rifle, and once your agents are good, your aimed accuracy gets close to ~200%, meaning you can reliably hit also with no visibility
- Double-barrel shotgun (up to late 1997) and CAWS as mentioned above
- Blackops smartpistol if you like using shields or want to give a lot of XP for new recruits (can fire 7 snap shots a turn if you don't move)
- TAC grenade launcher with gas grenades is THE weapon against humanoids and usually the way I wipe out manors in ~10 turns and Dagon and Red Dawn HQs. Just be careful not to gas yourself. Plastic aqua armor is good combo for this because it makes yourself immune to CHOKE damage
- MAGMA pulse rifle and CHEM clips can also be extremely deadly. At the point where this occurs you often don't need it anymore, though.
- Once the stats are good, there is really no substitute for Kukri in melee kills
- Pepper spray and boom box for improving your stats (especially bravery); collect some stunned enemies on a pile and repeatedly fire away until you get 13 xp on the stats (CTRL-SHIFT-E). For example syndicate labs and warehouses are ideal missions for these and typically at this point (in 1998) you have obtained already at least one of these.