Twists For Hollow Based Boolits

[Good Cheer]

Is there a method for calculating the twists needed for hollow based boolits?

[Outpost75]

Practical experience and empirical testing don't disappoint. S&W .38 Special revolvers with 18-3/4" twist of rifling show noticeable yaw in bullet holes firing wadcutter ammunition from 2 inch barrels. The 6-inch K-38 is accurate to 50 yards, but deteriorates beyond that. A Colt Python or Officer's Model Match with 14" twist is clearly better beyond 50 yards.

But a Bob Day PPC revolver using a 10-inch twist 9mm barrel will group factory match wadcutters well to 100 yards. Bill Duncan wrote several articles in The Fouling Shot testing various HB and DEWC .38 Special bullets at 100 yards, the best loads maintaining 3-4 inch groups.

[Recycled bullet]

Wow Outpost 75 I want one of those revolvers in my holster.

Sent from my moto g power (2022) using Tapatalk

[Outpost75]

Wow Outpost 75 I want one of those revolvers in my holster.

Sent from my moto g power (2022) using Tapatalk

Better wear Perry suspenders to hold up your duty belt then!

[Good Cheer]

So, no method known?

[Outpost75]

So, no method known?

There is, but the math for finite element analysis is daunting.

[Good Cheer]

Funny.

[firefly1957]

The calculations using sectional density of the entire bullet would account for the hollow point . But I read the headline wrong a hollow base is another animal altogether they travel more like a dart IF it is a deep hollow base.

Calculations are not real simple as many bullets use various compositions like the all copper bullets coming more popular now . As far as a hollow point the lead from the center of the bullet has less effect because it is much less mass then the material around it which is the spinning part that Gyro stabilized a bullet .

[Good Cheer]

I'm thinking that the shift in weight forward would be as calculable as a derivative of Greenhill's.
That wouldn't take into account the aerodynamic effects of lube grooves as fletching but yeah.
And there's the obvious that after the 1860's war everyone was pretty much off into other things any way.

[MT Gianni]

Twist would not be determined by weight but bearing length. The length of a HB bullet should be near to a PB version, though the weight differs.