Introduction

I've been playing around with a few non-EM Discharge Stubby builds, and so far this build is the one that I like in Hazard 6x2 (co-op then verified it on solo). I think that the EM Discharge build is still the best that Stubby offers when it comes to modded difficulty as it just scales so well, but I've found that a regular Stubby build can still do just fine even in the highest difficulties.
I have a solo video showcasing this build: YouTube: Solo Hazard 6x2 Stubby Engineer Check out my other Hazard 6x2 Engineer builds: Hazard 6x2 EM Discharge Hazard 6x2 Warthog

Build Explanation

Stubby

The secondary has insane AOE, decent single target, and some CC. Breach Cutter, along with Turrets and Plasma Nades all combined together gives Engineer powerful firepower. Therefore, what I'm looking for in a primary weapon is something that can help me efficiently and quickly deal with stragglers, spitters, and mactera. Ideally, I also want to have more single-target firepower since the rest of the build already has good AOE capabilities. When it comes to a regular (aka non-EM Discharge) Stubby build, there are only really two main setups: an electricity build and a direct damage build. Both have their advantages; I don't think one is necessarily better than the other. It's all about what you want to accomplish and contribute to the team. Based on what I want to accomplish, I decided to go with a direct damage-oriented Stubby build.

Overclock

There are two good overclock choices: Super-Slim Rounds and EM Refire Booster. The overclocks are interchangeable--you can use the same exact build setup and just replace the overclock to whichever you prefer. Technically, EM Refire Booster is the better overclock that gives you the better stats overall (DPS and total damage). However, the reason why I picked Super-Slim Rounds is because of the reduced base spread (resulting in 80% base spread vs EM Refire's 150% base spread). As I said, I want something that can also deal with both mactera and spitters. I found that in practice, shooting at those enemies with too high of a base spreads tends to make me miss bullets so I lost a bit of the dmg advantage that EM Refire has when it comes to dealing with spitters/mactera. But EM Refire is still very good when it comes to dmg against praes/oppressors since those are quite hard to miss. The loss of DPS/dmg is something I was willing to compromise.
Overall, despite using Super-Slim Rounds OC in this build, I actually recommend using EM Refire Booster for better damage and DPS.

Tiers

• Tier 1: Since we're going with a direct damage-oriented build, T1 damage is what we want.
• Tier 2: I think this tier is mostly preference.
  • I personally find myself manually reloading way before my magazine even nears empty. The magazine capacity (35 for slim rounds, 30 for EM refire) is more than good enough to work with. Along with reload animation cancelling, I find that I don't really need anymore magazine capacity.
  • I really like the reduced recoil the best. Even if you're shooting in bursts, it still helps for accurately shooting at medium-long distance targets.
  • The Base RoF of the gun is already pretty fast, I don't need anymore RoF.
• Tier 3: Once again, we're doing a direct damage build so we're going with T3 damage. Both on co-op and solo, I find that 420 is more than enough ammo.
• Tier 4: I think both of these are decent choices. Despite not taking T1 electricity chance, due to the playstyle nature (its an SMG) of this gun and its high RoF, you can still take advantage of the electricity procs. Because of factors like recoil and bullet spread, chances are that some or a lot of your bullets will be body shots rather than weakpoint shots when it comes to hitting grunts/spitters even if you're intentionally trying to go for weakpoint hits. I went with the weakpoint mod because I usually fire in small bursts and intentionally go for weakpoint hits even for grunts/spitters, so I think I get more consistent damage with the weakpoint mod.
• Tier 5: As mentioned in T2 explanation, I find 35/30 magazine capacity more than enough. Electric Arc is an amazing mod that gives you reliable CC. Especially since my goal in a primary weapon is to also deal with stragglers, this mod helps with dealing with those easier.

Breach Cutter

My secondary, Breach Cutter, build is the same across all of my Hazard 6x2 Engineer builds. I think Breach Cutter is insanely powerful because it provides both good AOE and single target whereas the PGL can only either provide and specialize in one but not the other. In Hazard 6 and up, it becomes increasingly more important to have both.

Overclock

A lot of the overclocks that Breach Cutter has are good. I personally prefer Inferno because I mostly play modded difficulty with players that are centered around a fire team composition. I still use Inferno though even on solo because the fire status effect is really good and scales really well because it can spread. Not only that, with Inferno you can one-shot spitballers. However, even if you choose to use another overclock, the build setup that I use is still good for other overclocks.

Tiers

• Tier 1: Having increased projectile lifetime means that you will have longer range. This is in particular synergizes really well with T5 Plasma Trail. With the Inferno OC, I rarely shoot more than two breach cutter lines at once, most of the time I only shoot one breach cutter because I want to take advantage of the both the fire DoT and the plasma trail DoT as much as I can. The increased range is also very helpful for sniping spitballers and breeders, for which there is many of in Hazard 6 and above modded difficulties. However, increased magazine capacity is also a decent choice because it effectively gives you 3 more ammo. It also allows for some more burst DPS, so in particular its nice against the dreadnaughts or to just quickly fan out an area of enemies in all directions.
• Tier 2: +6 ammo is way too good to pass up on. The other two mods can't really match its value.
• Tier 3: Quick Deploy is good so that you can actually use your Breach Cutter if enemies get really close on you, especially in Hazard 6/7 where enemies are way faster. Since I rarely fire more than two breach cutter lines, I typically don't manually reload the Breach Cutter and just rely on Born Ready perk to reload for me. Even if you don't use Born Ready, you can do reload animation cancelling so you don't really need the faster reload mod on this tier.
• Tier 4: Stun mod. Engineer has the worst survivability relative to other classes, you want the CC here.
• Tier 5: Plasma Trail for extra DPS and this mod is really good for swarmers/jellies/naedocytes. Honestly once you get used to aiming with one line, you really don't need Triple Split even against mactera. Against mactera, they typically go into a thin and straight formation that makes it easy to wipe all, if not most, of the mactera all at once even with a single breach line. However, I do recommend using Triple Split Line if you're playing the Mactera Plague warning.