Magazine length can be an issue. Also the rim on the hornet doesn't help. Most hornet magazines only hold a few rounds. The ruger holds 6, which is the most I've seen, but it's short. My solution was to shoot hornets in a contender and M38 (single shots) and make a new round to use carbine magazines:
saubier.com/forum/showthread.php?t=34387
So that is basically a hornet that works in 15 and 30 round magazines.
I think a fireball in a 223 magazine would be similar, and you could use just about any bullet you want and still fit a magazine. There are also some versions of "223 short" that use cheap and available brass with similar goals.