Originally Posted by
slingshot77
Barrel length doesn't matter (within reason). The spin on the bullet is put on the bullet by the twist rate not the barrel length.
If the barrel is a 1:7 twist & 7" long the bullet will still twist 2 turns at 14" of travel (or very very close to that anyhow). Now the bullet spin does degrade as it travels down range due to air friction but it exits a 7" barrel spinning at the same spin rate as it would exit a 14" barrel or a 32" barrel (assuming the same barrel twist of 1:7 for all barrels).
Using your above barrel length suggestion what is the bullet spin of a S&W revolver with a 1:18.75 twist with a 2" barrel? _____ Your thought would have the bullet not even spinning one complete revolution. How could that bullet stabilize if it isn't spinning?
But the bullet IS spinning because it has a 1 turn in 18.75" of travel put on it at barrel exit. So even though the barrel is only 2"long it has placed a spin on the bullet of 1 turn in 18.75" of travel but it is long out of the barrel before it reaches that 18.75" of travel.
A bullet spins longer inside the barrel with a longer barrel but it doesn't spin any faster in a longer barrel of equal twist rate.