neck size only ?

[Webster]

Agree. I would not expect to get a good uniform neck turn job without first running an expander in the necks. It will show up in the measurements.

My turning tool comes with a expander mandrel. I use it only to get a tight fit on the turning mandrel. I still say small high spots don't get pushed to the o.d. of the neck. It doesn't pass the common sense test. My requirements don't require getting OCD prepping cases. I still do a decent job. I only believe what the top competitors like Erik Cortina do. Too much noise and personal opinion on internet.

 

[6Creed73]

That very question crossed my mind some time ago, and as usual, I had to find out for myself.

What I found was that yes, the LCD did help mitigate the variance in neck thickness on my .308 cases I was testing (more so with the annealed brass than those that weren't annealed). Apparently the high pressure of squeezing action of the collet for sizing the neck not only lengthens the neck but also causes enough flow to spread the "high spot(s)" out, making the neck thickness just a little bit more uniform. But it doesn't doe near as good a job of uniforming the neck thickness as turning the necks does. Often, when just skimming the necks when turning them, you can easily see where one side of the neck is thicker than on the opposite side. Turning the necks gets all of the neck very even in thickness. The LCD will squeeze some of that thicker side away, but there's not near enough flow of the brass neck to make the thickness uniform all the way around.

Even though the LCD doesn't do as well and turning necks to get uniform neck thickness, the LCD does provide similar benefit as running mandrels through the neck to get a more uniform interior dimension for better seating runout.

Good to know!

 

[6Creed73]

My turning tool comes with a expander mandrel. I use it only to get a tight fit on the turning mandrel. I still say small high spots don't get pushed to the o.d. of the neck. It doesn't pass the common sense test. My requirements don't require getting OCD prepping cases. I still do a decent job. I only believe what the top competitors like Erik Cortina do. Too much noise and personal opinion on internet.

How doesn't it pass the common sense test? I'm genuinely curious about your thoughts on how a mandrel works. Imo the opposite is true, common sense would dictate that the mandrel is going to displace material. Where is the material going if not to the o.d.? The neck isn't getting longer, so it has to go outward. I agree, there is a lot of noise and opinion on the internet. But I think it's pretty much commonly accepted as to what a mandrel does.

 

[Homerange]

How doesn't it pass the common sense test? I'm genuinely curious about your thoughts on how a mandrel works. Imo the opposite is true, common sense would dictate that the mandrel is going to displace material. Where is the material going if not to the o.d.? The neck isn't getting longer, so it has to go outward. I agree, there is a lot of noise and opinion on the internet. But I think it's pretty much commonly accepted as to what a mandrel does.

100%
The mandrel is center referenced to the flash hole and being perfectly round and polished the neck inner takes its form and imperfections are transferred to the outer portion of the neck where they are either further displaced if the neck retains some malleability or can be instead turn off.

 

[Bill Norris]

How doesn't it pass the common sense test? I'm genuinely curious about your thoughts on how a mandrel works. Imo the opposite is true, common sense would dictate that the mandrel is going to displace material. Where is the material going if not to the o.d.? The neck isn't getting longer, so it has to go outward. I agree, there is a lot of noise and opinion on the internet. But I think it's pretty much commonly accepted as to what a mandrel does.

Following this. Inquiring minds want to know.

My turning tool comes with a expander mandrel. I use it only to get a tight fit on the turning mandrel. I still say small high spots don't get pushed to the o.d. of the neck. It doesn't pass the common sense test. My requirements don't require getting OCD prepping cases. I still do a decent job. I only believe what the top competitors like Erik Cortina do. Too much noise and personal opinion on internet.

O K so where does the high spots go then ?

 

[Homerange]

Following this. Inquiring minds want to know.

O K so where does the high spots go then ?

Is brass not malleable ?

 

[Mark611]

SS1, that's the approach I use as well, but also keep in mind not all brass is created equal, when I started loading for 6.5CM I started off with Starline brass, so I set up my tunning tools for that brass, just to skim or remove the hi spots, the cutter has not been adjusted from the initial set up, a short time into using the SL brass I purchased some Peterson Brass, first thing I noticed is the Peterson brass has a lot thinner necks, these cases didn't even come close to touching the cutter set up for the SL brass, I took 20 of the Peterson cases after prep without turning them, to see how they perform during their fire forming stages, too see what I get?

 

[Mark611]

Brass is way softer than steel, if your using a mandrel die that squeeze the neck it's going to form the brass, annealing softens the brass and helps the forming, also the flow of brass during the firing cycle helps to make things uniform, when you fire a case, it stretches or flows! reshaping itself, removing excess material to start with speeds up the forming process, Hi spots? what Hi spots?