@StarvingVirtuesLot to respond to and i have a slightly busy morning, but I'd recommend you give flechettes a whirl on kaleidoscope (last cap point), as there's a bunch of clustered enemies on that rooftop cap point and you can test if it overpenetrates or not rather easily with just a smoke grenade for cover.
I think double ought buck "should" be the premier unlock as it gives you the best multi-purpose round by the look of it if you have a decent degree of aim, slow velocity slugs are too fickle for me and generally always have been in previous games unless they were one-shot body inside a certain range as well (which imo, they should be. If they had the niche of also being lethal at longer range if you could manage a curved trajectory headshot, they'd have a purpose. I run a DMR or heavy round AR if i'm expecting people at medium/long range prone, not a shotgun)
All becomes rather academic though until they "fix" whatever bug is causing attachments and such not to work properly(tm), as i suspect that also carries over to shotgun ammo perks based on your observations.
I would also say though that i still think something is seriously wrong with shotguns in ADS-mode vs hipfire.
I'll try to get some more testing done tonight if i have time, but it seems there's a damage drop-off when in ADS vs not, which is fairly baffling.
Duckbill chokes/horizontal spread rounds were meh in previous titles, that role was (and maybe is until i can test them) much better filled by flechettes as they would do an equal amount of damage to anyone behind your primary target rather than just spread out a non-KO amount of damage to multiple targets side by side who would just murder you in return.
If the current flechettes also one-shot, then they're actually better than the BF4 variants if i remember them correctly where you'd need two, hence why you'd usually deploy them in a rapid fire shotgun of some kind.
Would make them quite viable on the 870 as well in that case and depending on the drop-off vs #00, possibly the best multi-purpose option.
On the upside, at least different shells on shotguns makes a bit more sense than multiple calibers on rifles do.
If you could check my observations on ADS damage dropoff vs hip to see if you see anything similar that might be useful though, my 870 (i'm sticking to that one for now for testing purposes) is genuinely worse while ADS and it's fairly noticeable, especially regarding one-shot kill distance on that rooftop point on kaleidoscope.
I've also noted something regarding the hitreg "bug" while doing this testing i think it's worth mentioning.
I've noticed the hitreg issue a lot more with the higher frequency of kills up on that specific map point, and to me it seems to always be a factor if there's scenery (stairs, pipes, walls, w/e) near me or the target when the bug occurs.
It's almost like the physical objects have hitboxes that extend past their visual reference frame, and as such you have to step out just a little more or wait for your target to clear whatever is interfering with hitreg before it suddenly registers hits again.
Since i did most of my testing up on said map, the ladder leading up to the helipad got me killed more times than i can count while zipping around up there in smoke and a shotgun, i dumped half a tube into a guy 10m away and scored no hits, and him none on me either despite dumping what looked like a smg towards me, then the bot stepped left and died in one hit.
I turn back and there's a new bot behind the stairs, one shot and dead that time because i guess the rng gods decided the stairs were open lattices rather than a block of cement on that shot.
Lastly, good job on your testing, i probably wouldn't have bothered myself and just written off the shotguns as garbage if you hadn't done the initial work!
Edit: i say 870 in these posts but you get the idea, old habits etc.
