Do I need to turn necks again?

[antelopedundee]

Chambers and dies vary in size and you are dealing with a belted case that headspaces on the belt and not its shoulder normally.

Example below is a new unfired rimmed British .303 case in a Wilson case gauge. This shows how short the shoulder is on a new case.

Below a fired .303 British in the Wilson case gauge resting on its shoulder. And this shows how much further forward the military Enfield chamber shoulder is located. And most belted and rimmed full length sizing dies will push the case shoulder back much further than needed.

Below a new unfired .303 British case on the left showin how short the shoulder location is. The middle case is once fired and the case on the right was full length resized and on the third firing the case had a partial case head separation.

Below rimmed and belted cases if reloaded should headspace on the shoulder to prevent case head separations.

Below another example of rimmed or belted cases below. Rimmed and belted cases dated from a age when cartridge manufacturing was not to the standards we have today. The case on the left is a newly manufactured .450 Martini–Henry and the case on the right was made in 1879. To put it bluntly rimmed and belted cases are outdated and from a time when manufacturing standards were very sloppy.

I don't deal with belted cases, but the best advice it seems is to pretend that the belt isn't there and treat them like regular unbelted cases. There is a discussion over at accuratereloading.com where a gent is having issues with a .338 mag with the likelihood that his rifle chamber is too long.

 

[bigedp51]

If you trim your cases with a trimmer that indexes off the case shoulder like WFT the turning cutter will always stop at the same point at the neck shoulder junction.

And after you turned the necks you pushed the shoulder back further and pushed the unturned area into the neck area. Meaning on a new case the shoulder is shorter than a GO gauge.

You either did not turn the necks down far enough the first time or pushed the shoulder back to far.

And to answer your question I would turn the necks again to the neck shoulder junction as resized. And even if you pushed the shoulders back too far and the shoulder does move forward, it just means any donuts will form much later.

 

[antelopedundee]

Zooming in on case u still got a little ways to go before u actually hit neck/shoulder junction with cutter. And yes body die makes your brass longer. No different than FL sizing as the box opens when it hit die it has to go somewhere and it can't go down. As u mentioned your neck die don't go down that far as most do not but if u don't trim down to neck shoulder junction eventually it will expand and then the dreaded donut will appear brother. Or worst case u can use steel wool and polish that step a little.

I thought the case he pictured was not the case after turning only. The case shown looks to have been fired and resized.

 

[Remmy700]

Maybe but looks like fresh neck turn

 

[Deleted member 107666]

So far, that case was neck turned as virgin brass, fired once, tumbled in steel media and run though a body size die

 

[bigedp51]

So far, that case was neck turned as virgin brass, fired once, tumbled in steel media and run though a body size die

And your body sizing die pushed the shoulder back forcing the unturned shoulder area into the neck.

Fire the cases again and see if the fired cases need to be neck turned again. Meaning after firing again where does the shoulder end up and the neck turning stop.

Most new cases have the shoulder shorter than the GO gauge, and when fired the shoulder will be blown forward to match the chambers shoulder. Meaning you should not see any unturned areas on the neck after firing. "BUT" you stated the case was sized in a body die and you now see some shoulder area in the neck now. This means you pushed the case shoulder back too far and made the shoulder area flow into the neck.

This is the only thing I can think of if you turned the necks to the neck shoulder junction correctly. So again fire the cases again and see what the neck and shoulder junction looks like.

 

[Deleted member 107666]

I'm lost on how I bumped the shoulders if the precision mic gauge read the same before and after the re-sizing? Shoulders grew .006 during firing, and measure the same after resizing.

Would marking the shoulder with a marker show me visually if the shoulder is being bumped next time?

 

[theosmithjr]

Turned necks before fire forming.

Ran these through a body die and now the thicker brass has pushed forward of the neck shoulder junction where I had turned necks to...do I need to turn these again back to the junction?

View attachment 146896

You're going to end up with the DREADED DONUT!

 

[Deleted member 107666]

I'm turning them again as we speak...damnit.

 

[jrock]

Yes by all means turn! I just ran into this myself as I didn't notice the change and ended up with doughnuts within 3 firings. Hand to push the doughnut to the outside and turn them down again and this time, well into the shoulder. Works perfectly now.

 

[kyshooter74]

You didn't turn the down far enough on the first go. You want enough to got into the neck shoulder junction so when fired and the shoulders move forward it is still just below the neck. So any doughnut forms there and not in an area of neck and bullet contact causing pressure issues and chambering problems.

 

[30BR]

I'm turning them again as we speak...damnit.

I have a standard f/l die I use to try and push the base of the neck back to the inside before running them in the mandrel for cutting necks the 2nd time. It helps make sure you are not cuttin too much

 

[antelopedundee]

I'm turning them again as we speak...damnit.

Do you have a pic of a case that was turned the first time? I usually do a junk case properll trimmed to length to make it easier to reset the turning tool if I change it. I use the Sinclair NT-1000 tool with carbide mandrels. A PITA for you to have to fully size and then expand the neck.

 

[Warbird2006]

Turned necks before fire forming.

Ran these through a body die and now the thicker brass has pushed forward of the neck shoulder junction where I had turned necks to...do I need to turn these again back to the junction?

View attachment 146896

Use Lee Collet die. Thim your brass and do not worry about trimming. If you use quality brass like Lapua, you will be fine without turning it. I know top F-Class and Bench rest shooters, they do this for years with great success and consistency.