Some years ago, I noticed how my H Bar with it's 1-7 twist blew up p. dogs better than the 22/250 with it's 1-14 twist.
So, I built two custom 1-9 twist 223's, Hart barrels, and a 1-9 twist Hart bbl'd 22 PPC. I had my own reamers so 14 twists in the 223 and 22 PPC were shot side by side, and Hart barrels were used in all builds.
I was really upset by what I had found out because I had spent $1200 on this 1-9 experiment.
I had established loads for the 223/14twists and 22PPC/14 twists.
Fact#1- Loads for the 223/9 twist and the 22/PPC ended up being exactly 0.5g less than the 14 twists.
Fact #2- Loads for the 9 twists changed more dramatically as the temps got hotter
Fact #3- It takes very little pressure change to change the accuracy node of a precision load. Just think of how a small change in seating depth can make a load shoot into a bug hole or open the group dramatically. Accuracy nodes are very sensitive, maybe as little as 2000 or less C.U.P.'s in pressure.
If you want to shoot a 9 twist or an 8 twist and shoot 40g bullets in 22 caliber, it is your hobby, do as you will. For me, I have learned my lesson, I twist and throat a barrel for the bullets I intend to shoot. I also worked up a load for a 40g with the 9 twist 223, it was super accurate, but it too had a very small window of accuracy in terms of the powder spread, OCW.
On another note, I have not seen where a 22 caliber 12 twist changes pressure on loads like the 9 twists did.
Mechanical engineers doing the math can "reduce to ridiculous" the tiny changes in pressure in the change in twist rates, but real world hands on experience is where the rubber meets the road. If a guy is not interested in super accuracy, well what the heck, it really is a non issue.
Having said that, accuracy is a relative thing, what is accuracy to one guy is a shot out barrel to another, etc.