neck wall thickness and neck turning

[yelnats]

Good Morning
Using my Mitutoyo, very accurate, inside micrometer I measured the case neck thickness of 200 of my 308 winchester and lapua cases.
Many are about one thou, inches, variance in the wall thickness and I have sufficient for a very close batch of cases for reloading
My questions are
1 if they are at or within one thou do they really need to be neck turned?.
2 is there a significant benefit at that level of difference?
3 If I neck turn should i do it with new or once fired cases?

thanks Denis

[AlanF]

Denis,

1 if they are at or within one thou do they really need to be neck turned?.
2 is there a significant benefit at that level of difference?

Personally, I get similar variation in neck wall thickness in 6.5-284 brass, and do not neck turn. I used to, but have noticed no increase in velocity variation since going "no turn".

3 If I neck turn should i do it with new or once fired cases?

Its definitely better after the first firing so the neck is smooth and round. However its not usually possible to do it in a tight neck chamber because of lack of clearance of the unturned neck. Towards the end of my neck turning days I had a no turn matching chamber for first firing.

Another approach is to do the turning in 2 stages, the first one just enough to chamber a loaded round, the second after the first firing.

Alan

[yelnats]

Hi Alanf
thanks for that. I am still sifting through opinions and technical data to see if I want to neck turn or not and every opinion helps me in one way or the other. I use redding competition bushing dies and they are great and the ammo is very accurate. BUT???????? can i do better???? is the question. thanks again.