Curious if a tight or loose twist has a measurable effect on pressures.
Thoughts?
It kinda does.
But if I have learned anything, your lands in combo with twist will really screw with things. Least thats what I have learned while messing with the 6.8
The OG 6.8 chamber remington fubar, have a short throat, 1:10 twist and I think a 6 land rifling. Pressure sign happened early, like in the 40k range
The SPC II chamber that Harrison came up with made the throat longer and he slowed the twist down to 1:11/11.25 and now the pressure range is up around 60k.
Now he has switched over to 3r rifling and back to the 1:10 twist and the speeds have went up with no affect on pressure.
He is coming out with a 224 Valkyrie barrel that has a 1:6.5 twist to stabilize the 90/95 smk with no velocity change.
I'm pretty sure that info is spot on.
Now to answer your question, I think a faster twist can show over pressure signs sooner than a slower twist. But unless the the twist rate is wrong and the chamber design is fubar then I think the affect are minimal
But like mention, bullet stability is were twist rates really come in to play