Reply To: Barrel liners ?
Hi Saltlake58! I lived in Murray for a few years once upon a time… I remember the T-shirts at the time that said “Welcome to Utah, turn your clocks back 25 years! 🙂 All the jive regarding twist rates is really very simple… it amounts to the proven scientific fact that shorter projectiles need a slower twist rate to be stabilized in flight, and longer projectiles need a faster twist rate to stabilize them in flight.
So how could this possibly apply to you someday? Well lets say you have a .25 cal. air rifle that shoots the JSB 25.4 grain pellets super accurate…and these are about 7 mm long. Then at some point you decide you want to shoot the 43 grain Eun Jin pellets for hunting game larger than squirrels…and these measure 11 mm long. Then lets say the barrel that shoots the JSB 25.4 grain pellet so well has a twist rate of 1-18″ or 1-20”. I can guarantee you that the Eun Jin 43 grain pellets will not shoot very accurately out of that barrel at distances like 50 yards or farther because they need a barrel with a rifling twist rate of 1-16″ lets say. How do we know this? Well this was all figured out many years ago by people smarter than me, but I will give you an example: A standard .22 long rifle bullet weighs 40 grains, and is 11 mm long, and is shot out of a barrel with a rifling twist rate of 1-16″, and it will shoot these bullets fairly accurately at 50 yards. But if we shoot a .22 Short in this same barrel it will not shoot accurately at 50 yards. Not because it shoots a lighter 27 grain bullet but because the .22 Short bullet is much shorter than the other one, thus it requires a twist rate of 1-20″ or even 1-24″ to be accurate.
One of my points is that the old adage “one size fits all” does not apply to barrel twist rates. Now Fredric Axelson knows that most of us are not familiar with all this, so he says that he is going to supply barrels with varying twist rates and match them to the pellets or bullets that shoot best out of them. (He says he even has a barrel with a 1-8″ twist rate now…I guess for shooting 5.56?) 🙂 Which means he is pretty much going to do most of the work for us and get us pointed in the right direction, and then we can experiment with various pellets and projectiles as we please. One example of this is that a few years ago I set up one of my .25 cal. Sumatra air rifles to shoot the 49 grain flat nose cast lead bullets from Hunter Supply, in one of my barrels that had a twist rate of 1-16″ that gave me an average of 108 ft/lbs of energy at the muzzle. That barrel shot these slugs and the Eun Jin 43 grain pellets both very accurately, but it would not shoot the JSB 25.4 grain pellets worth a darn. So I ended up with two Sumatra’s…one with the slug barrel and one with the standard 1-18″ twist factory barrel for shooting pellets.
But thanks to Frederic Axelson we will no longer need to own more than one rifle… we can just buy the appropriate barrel to shoot the projectile we require for whatever specific purpose we have in mind. And as an added super extra bonus we can adjust our regulator pressure and hammer spring tension ourselves, to give a given projectile the correct velocity in which to achieve its optimum performance. I am sure a lot of guys will share their data on the subject here so that most of us will only have to follow directions on how to set up a Crowne one way or the other. I hope any of this helps you or someone else understand the basics of twist rates as applied to Fred’s new Wonder Gun.
Best regards, Chuck