barrel length and twist

[bestill]

im seeking knowledge comparing barrel length and twist.    i shoot 100 gr blackhorn by weight  .060 veggie wads and 275 match hunters.  ive tested 3 different guns with this load setup and same loading force and primers.  

 gun 1 was 1-16 twist 25" barrel would shoot moa out to 300 yds   2300 fps 

gun 2 was 1-20 twist 25" barrel would shoot moa out to 400 yds    2350 fps

gun 3 was  1-22 twist 28 " barrel would shoot moa out to 250 yds  2400 fps  but most accurate of the 3 guns at 100 yds . 

want to learn more about design twist vs barrel length for specific bullet  ive done alot research with twist rates but is there a good read somewhere to learn more .

thanks

[7mmfreak]

Hands down the best books out right now are Bryan Litz's and Applied Ballistics for Long Range Shooting is the best place to start. There has also been some recent work with a Proof of Concept rifle that shows how unconventionally fast twist barrels extend sub-sonic ammunition range by up to as much as 7x what we thought could be achieved. I believe that is because the extremely long and heavy bullets were never shot through fast enough twists to stabilize them properly in the past and as a result 100m was about all they were good for. Fast enough is good enough and faster may not always be better as it can cause a bullet to become too rigid and fly with a nose up orientation which decreases BC (possibility with 1-16). Faster can help though as I mentioned with the Proof of Concept rifle and can also help as a bullet enters the trans-sonic range. As for the 1-22 shooting best at short range that could be due to a smaller magnitude of gyroscopic precession.