Neck Turning - Issue

[rivemor]

I typically neck turn my brass when converting cases from 7mm Rem SAUM to 6.5 SAUM but over the weekend I turned some 5.56 LC Brass to try to fix the concentricity of the case. I ran the test shooting my 77gr. standard load vs the same load but with the brass neck turned to see what difference it made. I was surprised to see the Avg. Velocity of the neck turned brass fall and both the Extreme Sp. and Std Dev opened up.

I would have thought with Neck Turning these numbers would be lower than the untouched brass. Is this typical with Neck Turning.

Thanks

 

[spife7980]

Did you change a bushing out or tailor your load to account for the differences in neck tension?