For the heck of it I decided to run three types of 170 gr .30-30 ammo that I had on hand through a little informal test at the rifle range this morning.
Temperature was 40 degrees, overcast, and with a slight north wind. The bullet launcher was my trusty iron-sighted 336 Marlin with the standard 20" microgroove barrel. The chronograph was 12' from the muzzle. The target was a row of one-gallon plastic jugs filled with water, at 25 yards.
Remington Core Lokt: Recovered from 6th jug. 132 gr, .552" dia. Muzzle velocity was 2118 fps.
Winchester Silvertip: Recovered from 6th jug. 125.6 gr, .584" dia. Muzzle velocity was 2167 fps.
Winchester Power Point: Recovered from 6th jug. 138.5 gr, .606" dia. Muzzle velocity was 2141 fps.
Unless one of these types of ammo shoots remarkably better from your rifle (and they all shot with about the same good accuracy from my Marlin), I don't know that I could recommend one of these over the other. They all have similar muzzle velocity, penetration, expansion and weight retention. The modest muzzle velocity of the .30-30, coupled with a large soft point seems to make for very good bullet performance.
I'd also note that at this same velocity level, some 300 grain .45/70 bullets I've tested were destroyed, and produced less penetration... Worth a thought.
Regards, Guy