I have not had much experience with .224 Sierra bullets. I have tried them several times, but have always found another make of bullet to shoot better. They are good bullets and do not know why I have had such rotten luck with them.
Now to your problem. Generally the octave is important to accuracy. Problem is, no two guns like the same thing, even if they are the same make and model. Generally speaking the bullets designed for a 22 Hornet has a short profile with a thin jacket. The short profile so it will work in short actions and the thin jacket so it will expand at slower velocities. The thin jacket also makes the bullet "softer" so it upsets in the barrel at lower pressures (velocities). Upsetting in the barrel assures that the barrel is filled so no gas leaks by the heel of the bullet and eroding it and to grip the rifling well. This is all general, because there are always exceptions to the rule.You can get a bullet with a heavy jacket to shoot well, but when it gets to it's target it will not expand or expand very little. If you are planning on using it for deer, then you need a very specialized bullet that will expand at low velocities without tearing apart. For littler critters, you want a bullet to "blow" up for a quick, clean kill.
I would start with a bullet that is designed for the 22 Hornet in mind. The Sierra #1200 (40 grain), 1210 (45 grain) are the best choices if you are wanting to stick to the Sierra bullets. If you want to expand to others, the Hornady 35 grain V-Max or the 34 grain MidSouth Varmint nightmare are two very good choices. Remington and Winchester make special .224 Hornet bullets too, I just have not had much experience with them. I have shot the Winchester hollow point (45 grain I think) a little and they shoot decently, but they are difficult to get - always out. The Remington Hornet bullets are a little rich to my thinking, after all, one of the reasons you shoot the Hornet is economy, at least it is with me.
One last thought about the 22 Hornet. Powder choice is critical. It does not take very much and just a .1 grain or .2 can make a whole lot of difference. Many swear by Lil'Gun, it seems to be a very good powder for the 22 Hornet. I personally, have had terrible luck with it. I have much better results using a light bullet (33 - 40 grains), W296 or H110 powder and a CCI 500 (small PISTOL) primer. My favorite load is 34 grain MidSouth Varmint Nightmare HP over 12.4 grains of W296 and a CCI 500 primer. High velocity, low pressure and fine accuracy. I got this load straight out of Speer #14 loading manual. I substituted the 34 grain bullet for the 33 grain Speer and used the starting point for powder. But that is my experience, many others have found other results.
BTW: my Hornets are 1 - 14" twist rates - all of them, I have 3. A stubbed H&R (22K), a Savage model 40 and a 10" T/C Contender. I can go on about twist rates, but that is another time.
Good Luck and Good Shooting
