Briefly, there was a time before the paratrooper stock, and before the burst fire speed was reduced, where the M39 ammunition was changed, but the gun itself was not. For that week, and that week alone I walked among my fellow privates with a pocket beno destroyer. The burst fire was on par with a smart gun, but more accurate, higher damage, better penetration. The moving accuracy one handed with a gyro + SMG stock was stupidly high. I was able to scare off warriors to ravagers. The 1 - tile hall was my kingdom, the benos my victims. Pairing all that with a machete and unga-juice if I could get my hands on it (And if not, punching two pain-stops before a charge), I was able to adopt an exceptionally aggressive playstyle well suited to close quarters as well as long shot halls. Two bursts and a boiler dropped, one burst scared off most everything else if it got too close. The three shots in rapid succession, with a tiny cooldown allowed for incredible damage output when loaded with AP. Even regular ammunition was very strong, two bursts scaring off armored targets. So long as I didn't engage alone and had guns behind me, I had no fear of being pounced and hurt, as my fellow ungas behind me would scare the benos off. I loved it, I took an SMG every round non stop.
However, now that the burstfire sucks and the weapon was diddled by my fellow devs, I stick to the classic pulse rifle shotgun combo. It was beautiful, but all good things cannot last. The SMG in my opinion is, well it's okay. It's more of a support weapon, which is what it's supposed to be. I'm still a bit annoyed that the burstfire is hands down useless now. Regardless, it's a good gun to take to swap up your playstyle here and there. It's better suited for CQC than the pulse rifle, and the damage output with AP is still very respectable on single-fire so long as you can land your shots. In it's present state, the SMG can still very easily solo any of the spitter caste, so long as they miss their neuro and you land 3+ shots. More effectively a warding weapon than a pushing one.
Briefly I took a revolver only for a few rounds. Why? Well you can stick the revolver belt on your armor slot, and another on your belt, for maximum speed loader goodness. Not to mention no one ever asks for M44 Marksmen loaders (AP - .44), so if you go last in Req, or it's low-pop, they're more often than not happy to give you their entire supply.
With a QFA, BC, Laser-Sight, and a Marksmen stock, the revolver becomes a very very shitty carbine. The accuracy goes to piss if you take a bayonet. Your only takes Should be a BC or EB, otherwise you won't be hitting shit, and if you do manage a lucky shot it's like a tickle. The strength of the revolver lies in the QFA and marksmen rounds. At close range the ability to put down range higher powered AP rounds than a regular pulse rifle enables good sustained burst potential, however you're a sitting duck when you have to reload. Not to mention, req will NEVER send down spare .44 rounds. So pack two bags of speed loaders and leave them at the FOB. In the end, you're better off taking a Pulse Rifle with AP, you'll have higher damage potential anyway.
The Revolver meme is amusing, but you will tire of it quickly, the accuracy and range penalties make the dream of a true revolver sniper near impossible. Even with a railscope, your bullets won't go where you want them too. It can be used as a warding weapon, but nothing much else. The chance to get a BC, which really does enable actual damage on the thing, is nigh impossible, and relies on a really dumb, or really meta-buddy req.
In the end, the Pulse Rifle is king of the PFC's arsenal, with all the other weapons serving niche, non-standard roles that only allow them to shine under specific circumstances. With the rest of the round spent floundering looking for those circumstances. If you know whats good for you, take a Pulse Rifle. Stick a Holdout Pistol (Assuming you can find one planetside) in your boot, a knife in your mouth, and forget everything else.
If you ever see me as SL (Stegnov Denisovich), this is what I'll be carrying:
Primary - Shotgun with Bayonet, Harness. Loaded with a mix of buck and slugs. Usually alternating. Perfect for corner peaking spit castes that get far too close to the jarhead convention.
Secondary - Pulse Rifle with BC/Bayonet, RDS, Masterkey. Keep it on the back as a harassment weapon. Webbing & Armor are full of AP mags.
Pockets - Med-kit pouch, with 'borrowed' advanced first aid kit from medical. If I can, a bottle of Inav & Bicardine in said med-kit. Large General pouch, for C4, binocs, booze.