.224 Barnes TSX/TTSX question?

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GIGGIDY

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Looking at trying the Barnes TSX or Tipped TSX in my Stevens 200 .223 Rem.

Looking at the info on the Barnes site, they recommend a 1:9 twist for the 62 gr TSX and a 1:8 twist for the 62gr Tipped TSX.

Why the difference in twists for the same weight of bullet?


Thanks,

:cheers:
 
I tried both in my 40X 223 with a 1:8 and neither would group at all so I put a sign "free bullets" on them at the Kamloops Gun show.... they disappeared.
 
GIGGIDY said:
I thought it was the weight not the length of the bullet that determined twist. Can you explain the difference for me? :confused:
Click to expand...

Bullet length is what determines the twist, not weight. That is why long nosed/boat tail target bullets need faster twists than flat base bullets with shorter ogives of the same weight.

The Miller Stability Formula is:

SG = (30*m) / (t^2*d^3*(1 + l^2))

Where:

m = bullet mass in grains
t = the rifling twist in calibres per turn
d = diameter of the bullet in inches
l = length of the bullet in calibres


The longer a bullet is for its weight, the faster the twist needs to be. For a practical example, a 220gr .308 bullet typically needs a 1:10 twist while a 240gr .44 Magnum bullet only needs a 1:16 twist for adequate stability. The shorter, fatter bullet is inherently more stable and needs less spin to remain stable.


Mark
 
mmattockx said:
Bullet length is what determines the twist, not weight. That is why long nosed/boat tail target bullets need faster twists than flat base bullets with shorter ogives of the same weight.

The Miller Stability Formula is:

SG = (30*m) / (t^2*d^3*(1 + l^2))

Where:

m = bullet mass in grains
t = the rifling twist in calibres per turn
d = diameter of the bullet in inches
l = length of the bullet in calibres


The longer a bullet is for its weight, the faster the twist needs to be. For a practical example, a 220gr .308 bullet typically needs a 1:10 twist while a 240gr .44 Magnum bullet only needs a 1:16 twist for adequate stability. The shorter, fatter bullet is inherently more stable and needs less spin to remain stable.


Mark
Click to expand...

Think throwing a baseball versus throwing a football...
 
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