Jack--I don't profess to be very literate when it comes to gunsmith knowledge and you seem to have some experience in that area. However, I did my research on what twist to use with the 30 grain bullet in the .17 caliber barrels as follows:
If you take a visit to the Lilja Precision Rifle Barrels, Inc. Web page
http://www.riflebarrels.com/ and go to the FAQ section and click on the question
"Q. Why do you have so many choices in twist rates?", then scroll down a bit, you will find a table of
"RECOMMENDED TWIST RATES." In that table you will see that the recommended twist rate for the 30 gr. bullet is a1 in 9" twist. I thought, perhaps, Dan Lilja would have some idea of what twist rate would be good for the 30 gr. pill.
Another resource I drew upon before selecting the 1 in 9" twist for 30 gr. bullets was the Shilen, Inc. Web page. Click on this link to see their list.
http://shilen.com/calibers.htm As you can see, they list
"a 1 in 9" twist for bullets heavier than 30 gr. and a 1 in 10" twist for bullets up to 30 gr."
The main bullet we have been talking about here is the 30 gr. Starke Red Prairie Varmint bullet. I don't know how it compares as far as length compared to weight, but it sure seems to shoot OK in my 1 in 9" twist barrel. In fact, my barrel seems to handle the 20 gr., 25 gr. and 30 gr. bullets equally well.
I have never had a desire to shoot a 37 gr. bullet in this rifle, but you no doubt have experience in that area that indicates a faster twist is necessary for the heavier 37 gr. bullet, but like I said, the 30 gr. bullet works just fine with a 1 in 9" in my rifle.