Reason I ask is that I have a bunch of bullets meant for the 22 Hornet but no Hornet rifle. I believe the diameter is .001 different, and that the Hornet heads are "softer" because they're used at lower speeds. Is any of this correct?

I do have a 223 and was wondering if I could use the Hornet heads in a reduced speed 223 load. Is this a reasonable thing to try? And if it is, can someone recommend a load or 2 to try?

GFP - You are correct on all your assumptions. Hornet bullets are undersized for the 223, which is actually supposed to be a .224 bore.

Now, as to what you could do with these bullets in your 223.....try them and find out. I think you will be pleasantly surprised. I've shot bullets intended for one cartridge in another of like caliber before with no ill effects.......other than they aren't going to be your best target bullets.

But in this case I'll bet my money they work pretty dang good in 223 as varmint bullets. I would expect the following:
1. You can load them about like you want. I would start with the suggested load.
2. You won't get top accuracy.
3. Because of the above, their light weight and less than ideal aerodynamic shape they aren't going to be a great LONG RANGE bullet
4. The WILL be fine for varmits out to 150-200 yds.
5. They will be VERY explosive and explode at the slightest provocation in flight.

Conclusion. Use them if you like. I see no big problem. When you think about it, this isn't near as wild as the 100 gr Speer "Plinker" bullet in a 30/06 and I've shot a zillion of them in my younger days with the pedal to the metal. It will work.

Just for the record, all "Hornet Bullets" (and barrels) are not .223. For many years manufacturers have used standard sized .224 barrels and bullets for the Hornet simply because it was cheaper than having to buy a separate size. And I think they will work fine for you.

I have used .223 Hornet bullets in my .223. My .223 is not a varmit rifle. Its an AK (SAR-3). The Hornet bullets were among the most accurate I've tried at 100 yards. I did not use a max load, I was down a few grains.

I have used them in a varmint weight barreled 223 loaded to 2600 fps. Their performance in that rifle was really no different than the 45 grain 224 Hornet bullets, which I use a lot of at that velocity.

Good Luck.

YES you can use the 30gr, 40 gr, and 45 Hornet bullets in your .223. Their accuracy will depend on the barrel's twist. Also, you may have to down load it a bit. I use the 55 gr bullet in my Hornet.

Thanks for all the advice. I was planning to download a bit, though I'm not sure what recipes that would take. The twist in my 223 is 1-9, which is probably a little fast for the 45gr bullets I have. (Crap, maybe they're 35gr, can't remember now).

Would a softer load lessen the negative effect of the too-fast twist rate?

If, for example, you have a Savage or Winchester with a 1-9" twist barrel, they might come apart, even with a reduced load. All you can do it try it, all you will be "out" is a few charges of powder. My Savage will destroy Blitzes and Super Explosives, but shoots normal softpoints okay. Load a few and try them, and let us know how they did.

Hornets have been .224 for the past 30 or so years.

The only "Hornet" load I've been able to belt out of my Savage .223 with any sort of speed or accuracy is the Nosler "Trophy" 45-gr. Some of the others come apart about 12 yards downrange; others are all over the place.

You definitely can load 'em down though. Half the fun of reloading is trying -- give 'em a whirl and see what happens!