Neck Reaming or Neck Turning?

[hdwhit]

I am one of the die-hards still trying to make the 5.7mm Johnson (.22 Spitfire) round work.

The case is formed from .30 Carbine brass. The case is lubricated, run into a forming die that starts forming the neck. The case is then run into a trim die that also further forms the neck and then the case is run into the sizer die that brings the case to its final dimension. To get the neck properly formed, the expander plug has to be in the sizer die when the brass case coming out of the trim die is first put in the sizer.

Because the process crunches a .308 diameter case down to .224, the brass has to go someplace and so the neck thickens. If the neck is more than 0.012 thick (it always is), it must be turned or reamed. At present, I use an inside neck reamer on my Forster case trimmer to both trim the case to length and ream it to the proper thickness. But after being reamed, the neck is too big to properly hold the bullet and so must be run through the sizer die a second time to correct the dimension; thus cold-working the brass.

I was wondering about turning the outside of the neck to bring it into specification without the need for the second trip through the sizer die but was worried about creating a stress concentration where the undercut portion of the neck joined the shoulder.

Does anyone have any experience with neck turning versus neck reaming that they could share and explain why I should choose one other the other?

Thank you.

 

[edwardware]

I've never reamed necks, but I do turn and anneal necks. Why not add an annealing step prior to final FL sizing? You should probably did that anyway after all that reforming, and it's not at all hard to do a consistent job with a torch, Tempilaq, and time.

 

[TRX]

The brass may not always flow evenly while the case is reshaped. You can wind up with one side of the neck a bit thicker than the other. If you run a reamer in, it will follow the existing mouth and your neck will still be lopsided.

If you do an outside turn over a mandrel, you cut the OD concentric with the ID while you're reducing the diameter, so your tension on the bullet is more even.

Theoretically, if the bullet isn't centered in the case mouth, it won't be entering the rifling precisely in the center either. In practice... some people claim it doesn't make any difference in their guns. Others like to reduce every variable they can in search of best accuracy.

 

[Walkalong]

I always liked to ream then turn. I have never done that conversion though. I was taking a lot off for a tight necked chamber and it may not be feasible to do both here.

 

[243winxb]

Outside neck turning does a better job.

Inside neck reaming should be done while the neck is held/being sized in a die. Like the vintage Lee tool. http://s338.photobucket.com/user/joe1944usa/media/Items for Sale -Gunbroker/SaleItems022.jpg.html

Ream if a lot of brass needs to be removed, but leave enough to outside neck turn for the final cut. A smaller reamer may be needed?

I reamed 30-06 and 243 win with the Lee, but it makes a final cut that was not as good as outside neck turning.

Maybe make 2 cuts while outside neck turning? Depending on how much brass needs removed.

 

[cfullgraf]

A number of years ago, I got the equipment to form 221 Rem Fireball cases from 222 or 223 Remington cases. At the time, I thought new cases would disappear from the market and i wanted to be able to shoot my 221 Rem rifles.

As part of the experiment, I tried reaming the neck as well as turning the outside of the neck. Reaming the neck just did not provide acceptable results with the effort I was willing to put into the matter.

Outside neck turning was easy and provided uniform neck thicknesses.

That is not to say that one can not get good results when neck reaming, just not me.

I'm currently working on a 22 Benchrest project. I'm outside neck turning the cases reformed from 6mm Benchrest.

 

[hdwhit]

Thank you for your prompt and thoughtful responses.

TRX wrote:
The brass may not always flow evenly while the case is reshaped. You can wind up with one side of the neck a bit thicker than the other. If you run a reamer in, it will follow the existing mouth and your neck will still be lopsided.

As soon as I read it, the light bulb went off in my head. Of course. Don't know why I had not thought about that before. Thank you.

 

[Walkalong]

Inside neck reaming should be done while the neck is held in a die

Before outside neck turning, I did mine in a Wilson trimmer with the case in the case holder (die?), and the reamer made for the trimmer. Like I posted, it may not be a good idea to ream first if only a little material needs to be removed.

 

[FROGO207]

Why I neck turn instead of ream.

 

[243winxb]

Inside neck reaming should be done while the neck is held/being sized in a die.

Added, "being sized". The Lee reamer would leave the brass ready to load and set with light neck tension for the bullet. The die supported the reamer as it cut.

 

[murf]

if you are getting "doughnuts" at the neck/shoulder junction, it is best to do what walkalong suggests in post #4. with that much forming you should have plenty of material in the neck to do both.

luck,

murf