They aren't particularly light, but with good bullets a Sig 556R or Ruger Mini 30 with a folding stock would fit the bill. The 7.62x39 with the right bullet is close to the 30-30 in power, and it would certainly do the job. No need for a large magazine, a small Magpul plastic one would help keep weight somewhat limited.
I have a Sig 556R wearing a Trijicon 1-4x scope with the triangle reticle that doesn't lend itself to precision shooting. Even with that hitting a 12oz can at 100 yards from a rest is easy, and 50 yard groups are under 1". It's an accurate rifle, just limited by the optic and trigger at longer range.
FWIW I have a 9mm Kel Tec carbine also. It functions well with good quality magazines when it's kept clean. Shoot 150 rounds without cleaning and it will start acting up.
I've read that polymer will flow under pressure over time. I sold a Kel Tec SU-16C because the scope's point of impact would consistently shift over time. I'm guessing this was the issue. The rifle was accurate, but it couldn't be put away for a long time and relied on to hit the same place when it came back out. That scope is now on the Sig 556R and has had no issues. I'd personally avoid putting a red dot or scope on anything with a polymer rail after that experience. That SU-16C could work but would not be my choice.
Handguns are harder to learn to shoot well. I'd be comfortable at 50 yards with my Sig 1911 10mm, but I can't shoot my G20 that well that far. I'd prefer the takedown rifle if it was for hunting and not defense.
All that said, if I was buying something new the Chiappa 44 mag carbine would be an easier packing and shooting option. I'd likely look for one of these on Gunbroker. The 44 version is much lighter than the 45-70 version. A red dot or scout scope can be installed if desired.
www.chiappafirearms.com