"Before they captured tons of plasma rifles (and before they even existed), what do you think the resistance had the most luck with?

I'm not a weapons expert, but I assume they generally wanted heavier ammunition...7.62 would be preferable to 5.56. And obviously a .50 Barrett would be very good, but what about more conventional weapons? Would they want to use a M14 with armor piercing ammunition? What other guns?

And what about sidearms?

I'm just trying to get a good idea for my fic, but this is also an interesting topic. Keep in mind, these weapons would mostly be used against T-600's or other primitive models."

"Don't think, that they have some options in this, when US Army have standard weapons with 5.56 NATO rounds, they must rely on what they have.
But 50.cals should be most effective in terminating Terminators.
Maybe even some flamethrowers (CPUs and heat are not good friends)."

"In T4, John Connor carried an HK416. That was the only good thing in the entire movie.

5.56x45mm is garbage when it comes to penetration. Tungsten M995 is rated for 1/2in of steel. That is plain old steel, not titanium or some advanced alloy.

Why 30-06? My deer rifle is an aught-six, and I dislike the 308 for all but replacing my beloved cartridge, but there's no reason to use 30-06 instead of the more common 7.62x51mm. If you need greater velocity, then pull some 7.62's and load them into 300 Winchester Magnum cartridges. I have been considering doing this in my own fanfic.

T-600's are said to be titanium even in T4, but the T-600's are clearly shown to be covered in rust. TITANIUM DOES NOT RUST. Even if termies are made out of iron, I can tell you that a .357 or .44mag will do nothing to them.

My .50AE Desert Eagle will barely leave a mark on 1/2in high grade steel plate, but it punched a nice hole in the side of a 1970's Dodge Powerwagon engine block(which is made of iron).

If they ARE titanium(as is canon), then I can't see any handguns damaging them. The 460 S&W might, but only because of the velocity. Titanium is just too durable for anything except very fast projectiles to damage it."

"what about a titanium tipped tungsten round or perhaps for mass, but hard to get tungsten, steel cattridge? if that is possible that is "

"Also, the most effective napalm the US ever used was Napalm-B which is benzene, styrofoam, and gasoline. In T1, that tanker truck went up with a T-800 inside the cab, and the machine only took damage to its leg."