Thread: Neck turning

If you end up with Forster gear then be prepared to find the mandrels are quite undersized. They advertise 0.002 - 0.0025" under but I have a 7mm mandrel here that measures 0.2805". The issue is that the brass needs to necked down to be a tight fit on the mandrel prior to turning. I don't reckon Forster have got this quite right because this level of undersize may be smaller than most unmodified expander balls will produce. Turning on a loose fit will likely degrade concentricity rather than improved it. The same for using bushing dies for this step where a bushing size may need to be purchased specifically to take the necks down to be a snug fit on the mandrel.

Puffin, I understand your concern.
Here is how I see it to answer your question:
Either you are shooting super accurate rifle with tight custom chamber, on bench rest ,and then going with something else than top quality brass like lapua is a false economy. That lapua brass will be already very good in neck concentricity, thickness and tension. So the neck turning you will do on it will just make it perfect. And the small irregularities will deseapear after the neck turning.

Or you are shooting a hunting rifle ( custom or not) but with a standard chamber : if you buy good quality brass for it then you do not need to neck turn, or you have a more average brass and then you could see an improvement and a justification for turning that brass to make it more consistent.

I turn my brass for my bench rest rig (30 BR), used to for my 6.5 creedmoor when I was necking down from 308 brass, now good factory brass is available from Norma.And I necked turn a small batch of 300 whisper and 308 for my subsonic reloading, and see better consistency on target.

Originally Posted by Friwi

Puffin, I understand your concern.

My concern is not foremost about accuracy but about safety around tight necks.
I'm currently looking around at the available reamers for 6.5x47. The reamers where I know the manufacturer are all PTG and there appear to be 2 different profiles, one with a tighter neck (0.292" ) and the other wider (0.2945). Loaded rounds using Lapua brass are 0.290 across. I think you would need to be very careful with just 0.001" all-around clearance. For me the narrower chamber would dictate skimming the necks to take a loaded round down to 0.289" minimum, but I'm interested to see what others think is a safe neck clearance margin. I think most would accept the wider reamer as "no turn" for brass that gave a 0.290" neck for a loaded round.

Originally Posted by Puffin

The same for using bushing dies for this step where a bushing size may need to be purchased specifically to take the necks down to be a snug fit on the mandrel.

Forgot to add that with a bushing die not being able to size right up to the neck-shoulder junction then not all the neck can be turned so the case will end up with a donut. Really need a conventional die just for preparing the cases for neck turning !