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1) Measurement and math:
If I put a 0.500" pin gauge in a Lee 243 Lee collet neck die collet, it has 0.440" hanging out.
If I put a 0.350" pin gauge in a Lee 243 Lee collet neck die collet, it has 0.367" hanging out.

angle = inverse tangent = inverse tangent of rise over run= tan^-1 [.44 -.367]/[[.5-.350/2] = 44.2 degrees.

2)Kindergarten:
If I put some play dough on a 243 case and shove it in the collet, pull it out, and compare the dough shape to a 243 case and a 257 Roberts Ackley 40 degree, and take a picture.. the collet looks like it is greater than 40 degrees.

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