Mathematical Challenge re: CE 399

[David Josephs]

I don't doubt that CE 399 was fired from the rifle found on the 6th floor of the TSBD. That is not at issue here. What I am trying to determine is the rate of twist of the rifle found on the 6th floor.

Sorry for sounding stupid Bob... in one sentence you know that ce399 came from C2766
in the next you are trying to determine the rate of twist of C2766, the rifle found on the floor... ?? Wouldn't that be a function of what we see on CE399?

Or are you saying C2766 was not the rifle found on the 6th floor.

Let me try some examples to try and understand you regarding the marks on CE399, which can be measured

The barrel of a 91/38 FC is 53.8 cm or 28.1811 inches.

http://kwk.us/twist.html is a twist rate calculator I found online - I used 2.8 inch length, .268 diameter, 2000fps? and 8.9 bullet SG and got a 3.6 inch twist rate....
Does this mean that the bullet spin 28.181" / 3.6" times before it left the muzzle ?

Unless there is a manufacturer's spec on the twist rate i seems to me we have to have a bullet fired from the rifle to determine that rate
DJ

[TABLE="align: center"]
[TR]
[TD="align: left"]nputs[/TD]
[TD="align: center"]outputs[/TD]
[/TR]
[TR]
[TD="align: right"]bullet length[/TD]
[TD] in[/TD]
[TD="align: center"]twist in[/TD]
[/TR]
[TR]
[TD="align: right"]bullet diameter[/TD]
[TD] in[/TD]
[/TR]
[TR]
[TD="align: right"]muzzle velocity[/TD]
[TD] fps[/TD]
[TD="align: center"]errors[/TD]
[/TR]
[TR]
[TD="align: right"]bullet SG[/TD]
[TD][/TD]
[TD="align: center"][/TD]
[/TR]
[TR]
[TD]bullet SG values:[/TD]
[TD="align: center"]11.3 lead
8.9 copper
8.5 brass
7.8 steel

[/TD]
[/TR]
[/TABLE]

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