The Sierra GameKings and ProHunter bullets are both simple cup and core projectiles. Last year, shooting the 150 Game King, a boat tail spire point, into wet newsprint from 75 yards, I recovered 2 that the core had seperated from the jacket. These loads were not traveling faster than 2300 fps and were more likely in the low 2200's.
I plan on doing some similar testing using the Hornady 150 SST, this is a quick opening bonded core bullet using a plastic tip like the Nosler Ballistic tip design. Another bullet that while costly should work quite well is the Nosler 150 Partition. I am going to try out some Nosler Partition 180's as soon as I get them paid for. The Speer 180 Mag Tip is another bullet that has good opening characteristics at low velocities that should work nicely at 30-30 velocities. Finally , the plain jane Speer 165 Spire point that is a Hot Core design should also work well at the velocities the 30-30 is capable of in the Handi 22" barrel.
There are actually quite a few good bullets to choose from that are spire point designs that will funtion fine at 30-30 velocities. The "trick", if you would, is generally using bullets of not more than 165 grains. These bullets are designed to perform at 300 to 400 yards from the 300 Savage, 308 and 30-06. So long as the range doesn't exceed 200 yards, the velocities attainable from the 30-30 22" Handi Rifle are good matches for the design envelope of these bullets. The trend in jacketed bullet design these days is away from hard bullets and toward bullets that expand rapidly, that will shed the mushroom if the expansion is too violent (a result of too high impact velocity) while leaving a hard base portion of the bullet that will retain about 65% of bullet weight and continue to penetrate even when the nose has been torn off. The lower velocities of the 30-30, falling in the range of the low end velocity performance window gives us bullets that perform nicely while increasing the practical range of the oldtimer.