Yes, acknowledged. One would think that a decrease in rotational energy might allow for a marginal increase in translational energy (velocity).
A few weeks ago, I did the math to see to what extent the 1:3 twist (rotational energy) contributes to the overall projectile energy (translational energy + rotational energy). Interestingly, the rotational component contributes only a little more than an additional 5%. I was surprised and can only assume that what is seen in the many gel block tests reflects the 'shear' force interactions with tissue (viscosity), which is not explained by the energy math alone.
I have reached out to Lehigh Defense suggesting projectile development (solid copper) that might mimic their XP/XD lines of projectiles, which would fully exploit this high rotational property. An XD style projectile in a heavy subsonic should be crazy devastating and I am speculating the wound channel it will create in a gel block will be impressive. We'll see what they develop.
They also have two other lines of projectiles that are a little more 'classical', one being the Extreme Chaos (fragmenting) technology, and the other being a Maximum Expansion technology. None are commercially available at the moment, but development is underway and prototypes might be released in the near future.
Anyway, for now, with the Maker projectiles, I would think you might safely pick-up a little extra velocity with the 1:6.5 twist barrel. However, from the math alone, you're likely looking at 3%-ish. When I hear from Paul, I'll post in the thread.
The Maker bullets are on the way...so soon as they get here I will load some up.
Take off muzzle device and see what happens with speed and twist rate.
But check their only listed load for accuracy and velocity first.
It will be interesting as I can add 1000 fps to lead core bullets and they do not blow up in the 6.5 twist.
Which appears to be dependent on RPM of the projectile.
So 2000 fps which will not be attainable, with 350 grs, but might be safe in a lesser twist barrel.
I will run them at 1500 fps to 1700 fps for accuracy and max velocity, see what happens, as the velocity increases.
I have serious doubts about the gel test vs flesh, as the FBI does not consider the clear gel to be valid.
Its just a visual, in a consistent medium, animals have hide, bone, flesh, and a variety
of tough connective tissue.
Bullets stop rotation, break up, tumble, change coarse.
Ya can't put your finger in a bear and dig out a bullet.
Energy input is exact and can not be destroyed, but changed.
So any energy used to impart spin, must be subtracted from muzzle velocity, as energy used from the exact powder charge.
So it it cost 20 fps to spin a bullet faster than a slower twist...the slower twist will be 20 fps faster in muzzle velocity than the fast twist.
So the energy would always be an equal amount applied on the target.
The question is how the equal energy is applied,.. larger wound, less penetration.
Sharp pieces of bullet would cut easier than dull pieces, but that is more random in performance.
Does a bullet that makes 4 turns through a game animal instead of 2 have any more killing power, ...its random as to how & where the arteries and blood vessel are located with respect to bullet rotation, as the bullet strikes, and how resilient those body parts are, plus any rotation can stop instantly, petals break off, bullet goes way off coarse, sometimes 90°, or tumbles.
I find a lot of random bullet performance when shooting big game, with any bullet.
They all seem to kill over time, but it boils down to what has worked for you individually... and subsonic adds a whole new barrier to modern bullet performance.
So any new manufacturering ideas and sharing information may help in the subsonic endeavor, if there is a profit in promoting it, so far there are quite a number of bullets to be tested for various calibers, with alot of mixed reviews.
So I'll just report on what my testing shows, useful or not,...it gives me something usually fun, to do.
As I do not plan on any subsonic hunting, big heavy bullets at high 338 magnum velocity are my style for that..at close range... so a 8.6 sub could also work here. Or the old bow and arrow for stealthy times.