on the right track
The comments regards "types" of rifles are on the right track. The .30-30 is typically and traditionally a lever ctg. Oh yeah, there are a few Sav 340 about, and maybe a custom Ruger No1, some HR single bbls, but usually, we're talking Winlin carbine.
Some Winlins are not easily scoped. Some have the traditional half cock safety, which I believe is not fully understood by all shooters. The lever carbine is not thought of as an accuracy "platform" though some will surprise you. So-so triggers on most. All this works against the .30-30.
Plus factors: Handy. Flat, light, and ammo still pretty common. The .30-30 wins hands down in versatility of ammo, heavier slugs, even factory Nosler's! Lots of big critters have been taken efficiently w/ a Winlin .30-30.
The x39 is a semi and bolt ctg. Take the x39 out of its typical bullet hose and into a quality bolt like the ruger 77-II or a CZ, and one has a useful, light rifle for typical 150 lb whitetails. Easily scoped, good triggers, simple box mag, time proven safety and manual of arms.
We could use a quality x39 hunting load, lighter than the 150 stuff, heavier than the 125. Oh but for the return of the Sierra 135 slug, or a factory load that used same.