I'm interested in this too, would love to throw a 22cm bbl on an old marlin x7 of mine.
I was going to get on here and explain that over stabilization is bad and talk about the bullet "going to sleep", and recommend that 1:8" is probably all you need. ....then I input some data on stability calculators and I really think that a 1:7.0" is exactly you need.
That being said, idk exactly how long a 95gr .224 SMK is. But it's gonna be longer than a 95gr .243 SMK which is 1.180". Let's assume your 22 cal bullet is between 1.20" and 1.24" in length. I also don't know the velocity you can push this heavy of a bullet (or what length bbl you'll end up w) but let's assume you can hit 3000fps, which is mildly generous but perfectly possible.
At 3000fps and a 1.240" length, .224 95gr bullet, you end up w a stability factor of of 1.52. ....which is the minimum you really want. IMO, you don't wanna go over 2.0 and never over 2.5. Just my two cents. But 1.5 at the muzzle is thought to be pretty ideal.
Now if we shorten the length to 1.20" long but keep velocity the same, then your stability factor only goes up to 1.67. That is anything but over-stabilized. This is good stability.
Bottom line is you need to figure our your exact bullet length and expected muzzle velocity to be sure, but I honestly think a 1:7.0" is the minimum you will need.
And I swear I thought a 1:8 wudda been sufficient.
someone correct me if I've made a mistake somewhere.
Btw over-stabilization is true reason (imo) that you can have significantly tighter groups at distance (than at closer targets) after the bullet goes to sleep. Basically, over spinning the bullet causes it to wobble on its longitudinal axis rather than spin cleanly and symmetrically. Litz talks about this in his books, so trust what he says before me. But basically the tip creates a clover leaf pattern about the long axis of the bullet until it goes to sleep, and then settles in such that it spins cleanly without causing the tip and base to wobble around the longitudinal axis. Imagine a football wobbling from too little spin; it's basically the same thing. So you want just enough spin that it's still spinning sufficiently when it gets to its target. Typically, a stability factor of 1.5 is sufficient for this bc it won't drop below 1.0 before it hits its target.
Also, for 99% of us, under stabilization is the only true problem we need to worry about. Over stabilization isn't a practical problem that affects much except those edge cases.
Just my 1/50th of a dollar. Let me know if I'm missing something.
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