First of all, let's get pistols out of the way.

It's almost never worth spending points on pistols, meaning that you should be using the M9 or Makarov most of the time. It's still worth understanding the differences between the pistols, though.

The M9, Makarov, USP, and G17 all deal the same damage. They will down a target with 2 torso shots, 3 limb shots, or 1 torso shot + 2 limb shots (1 limb shot + 1 torso shot won't work). The TT and M1911 deal more damage, resulting in less required hits when shooting through walls, and they can down with 1 torso shot + 1 limb shot. Any pistol will kill with a single headshot (not considering shooting through walls).

If you are willing to spend a point on a pistol (perhaps you're using a shield or simply choosing to play with pistols only), I still consider the M9 to be the best Marsoc option, while the USP is the best Volk option. The M9 is free, but it is my favorite pistol in the game. The G17 has a slightly larger capacity, but I find the sights on the M9 to be much easier to use. The M1911 has a tiny mag size of 7, which makes the M9 an obvious choice. Looking at Volk, the Makarov is easily the worst pistol in the game, with a small mag size of 8, low damage, and terrible sights. The TT is better with its high damage, but the USP has a considerably larger mag size of 13, and is simply a good-feeling pistol all around, making it my favorite Volk sidearm.

In short, always use M9 on Marsoc, usually use Makarov on Volk because it is free, and use the USP when you don't mind spending the point on Volk.

With so many good assault rifle choices, it's not easy to figure out the good ones, but a couple really stand out.

For Marsoc, I mainly use the MK-18 for the specialist class. It it only costs one point, it has full and semi auto, it has AP, it has Marsoc's amazing red dot sight (RDS), it can take a suppressor for 2 points (specialist and designated marksman suppressors cost 2, rifleman suppressors cost 3), it has a 30-round mag, and it has a great reload (mag drops with a button, and its bolt locks open so that you never need to rack it). It shoots straight and has all the big advantages you want in a rifle. An alternative is the AK5C, which is extremely similar, with the main differences being a more expensive suppressor and access to the 4x scope. Either way, stick on a RDS, put the dot on the enemy, and pull the trigger!

For Volk, the AK-12 is an easy choice. It shoots great, costs one point, and doesn't have any real weaknesses. You have to rack the bolt, but the bolt is very nicely placed. I commonly hear people say that they prefer the AKM, but the AKM costs 2 points, does extra damage that isn't too noticeable (only makes a difference through walls besides killing with 2 limb shots instead of downing), and has terrible bolt placement. Take the AK-12 and put a holographic sight on it; you'll be set for any map! There's really no fantastic alternatives to the AK-12 for Volk. The Specialist's G36 is good, and even has the lock-open bolt, but its sights are placed very high above the barrel, making it easy to shoot your cover instead of over it.

Want to snipe across Downfall? There's a couple things to note.

First of all, the Volk 12x scope isn't NEARLY as good as the Marsoc 12x. It's very far forward and small. Even with a stock, I find it to never be worth using.

When on Marsoc, I have two sniper options that I like. The L96 + 12x + suppressor + AP is extremely deadly. The L96 (bolt-action rifle) not only hits like a truck, but it gives you free AP, letting you do all 3 of those attachments. You can take shots across Downfall without anyone ever realizing where you are. The other option I would consider is the SCAR + 12x + AP. It's less stealthy and you may not kill in one shot, but you can send a lot more shots down range.

For Volk, if I wanted to snipe despite not liking the Volk 12x scope, I would choose between the SV98 (bolt-action rifle) and the SKS. The SKS is famous for shooting extremely straight.

As a side-note, most players find using scopes to be extremely difficult without a rifle stock. If you're unsure of how much of a difference stocks make, trust me, it's a massive difference.

Also, 4x scopes are considered to be fairly worthless by most of the playerbase. They provide little advantage, and parallax (your shot not going straight to the crosshair because your head isn't perfectly centered with the scope) makes it not as accurate as a simple red dot or holographic sight... In any case, spending 4 points for a 4x makes little sense.

Need more points for grenades and other options? Perhaps you should consider saving 2 points by forgoing the RDS or holo! However, many guns have sights that are very difficult to see, others have sights that simply shoot very high or low, and some guns have sights with both flaws! It's a good idea to know which guns have usable sights!

Volk is lucky with the AK-12. Not only is it a great weapon in general, but it has very nice iron sights that are sighted in perfectly. It feels like a laser at any range.

As a stock user, I look for weapons that fit the same stock. If I'm going irons, I have to use the AK-12 on Volk. For Marsoc, I found the matching weapon to be the M14. Now, the M14 isn't great in general, but it has fantastic iron sights and fits my AK-12 + irons stock.

Whenever you want to try using a weapon with iron sights, take it to the range first! The AKM and AK-74u are tempting weapons to use with iron sights, but their sights don't put your shots anywhere near target. There are others, too, but those are the worst.