Most guns chambered in it will be at the slower end of the twist. Even .22LR conversions, so yes, the lighter pills more likely to produce accuracy as heavier pills can't be spun enough to stabilise.
Lil'gun pretty much gave the cartridge a new lease on life. An Ackley or K- reamer up it will improve it again.
4198 should get you decent velo.
.222 and .223 kinda do the same job or better. But I do have a soft spot for the little hornys. And that original soft-tapered cartridge, rather than a hard shoulder.
"Ahh, the good ol' days"
Stick to the light pills if they're working for you. I think speer (?) do a 40gn SP which is pretty effective on game.
I have a swag of mixed hornady I need to go through and maybe get rid of but I think they're all heavier, 55gn+
In the right place, if you're close enough, they'll kill anything in NZ. Quiet and low recoil too, so a good cartridge to progress the younguns to, from rimfire.