[tmac6361]

I was wondering if anybody could tell me about the twist rate in rifles or suggest a web site for info. Is a 1:11 better than a 1:10? Does the speed of the cartridge matter? Does the rate mean that in 11 inches the bullet spins once? Any info would be great thanks.

 

[Guest]

yes 1:11 means 1 revolution in 11". the weight of the bullet is the major factor in rate of twist. the 223 has a pretty wide range of weight so if the rate of twist is 1:9 the heavy bullets won't shoot as well as from a 1:10. i believe i got that right. front stuffers are like 1:24. there are a lot of factors that go into it BC, weight, speed, pressures, play a role in choosing a rate of twist but its easier to choose a bullet to match rate of twist than the other way round.

 

[Karl.Luhr]

Twist rate selection

I don't remember the formula but there is one to calculate the optimum twist rate for a cartridge.

I takes into account the speed of the bullet, its length, and its diameter.

I do remember for example the magic twist rate for a 30-06 is something like 1 in 10 is you are pushing a standard 180gr lead core bullet at 2700fps. A solid non lead core bullet would be longer and then the optimum weight of this non lead bullet would be a lighter weight.

This then changes with something like the .223 using a 1 in 7 twist for the long 62gr at 3100fps. The shorter/lighter 55gr wants 1 in 12 at about the same speed.

Look at the various web sites for bullet manufactures and I think you will find the true formula.

 

[Body Bag]

Depends on the caliber and load. The twist rate is part of what determines the accuracy. That is why you find what ammo your gun shoots well. (I think)