Question about rifle twist rate

[chahahc]

I was wondering (instead of keeing a flat 1:10" the entire barrel length) if increasing the rifle twist rate as the bullet travels down the barrel would be of any benefit, like increasing velocity. For example, the rifling at the throat has 0 twist rate, then gradually increases to 1:30" @ 8" of barrel length, increasing to 1:20" @ 16" barrel length, increasing to 1:10 @ 24" barrel length,

The idea behind this being that faster twist rate = high chamber pressures, so having a lower twist rate closer to the chamber (where the pressure would be highest) would lower the overall chamber pressure (kinda like a pseudo freebore, without the decrease in accuracy of the bullet slamming into the rifling)...so then maybe you could use more powder? Or something like that. My google-fu hasn't been able to find anything about this.

 

[dubbleA]

Try googling "gain twist"

 

[chahahc]

Ahh thanks, I didn't know what exact term it was .

 

[MCMXI]

The idea behind this being that faster twist rate = high chamber pressures, so having a lower twist rate closer to the chamber (where the pressure would be highest) would lower the overall chamber pressure

Why would a faster twist rate increase pressure?

 

[adelbridge]

Why would a faster twist rate increase pressure?

bullet travel increases per same length of barrel with faster twist (linear + rotational travel) Increased bullet travel means more time in bore and potentially more efficient burning of powder.

 

[MCMXI]

bullet travel increases per same length of barrel with faster twist (linear + rotational travel) Increased bullet travel means more time in bore and potentially more efficient burning of powder.

If the twist rate had a significant affect on pressure, you would think that QuickLOAD would have an input for it.

 

[rcmodel]

The .460 S&W revolver uses gain twist to supposedly get a few more FPS out of it..

And it was very popular 200 years ago with black powder rifles, because it kept the soft lead slugs from stripping out in the rifling and didn't foul with black powder residue where most of it was burning.

There is little to be gained with smokeless powder at normal pressure & velocity now.

rc

 

[Jim Watson]

Bartlein Barrels is offering variable rifling twist, anything you want from H. Pope gain twist to a very slight gain just to be darn sure that there is no loss in twist which is detrimental to accuracy. I don't know how many T Style barrels they are selling, but it is a regular option so somebody must think it helps.