Seperated necks

JonathanK

New member
I thought I would share this picture of what happened to a couple of cases of mine at the Crawfish. Im pretty sure the cause was my turning of the cases too far on the shoulder.

2010-05-20210023.jpg
 
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necks

Your right the necks are turned too far down. I had the same problem once.
 
Neck trimming

Jonathan,
I am not an expert but it looks like it may be a hot load rather that a trim problem. I say that because I trimmed up some new 30PPC cases several weeks ago and was fireforming and after shooting 3 cases numerous times one of the necks was showing a black ring that would not clean up. Turned out to be I had slightly cut into the shoulder and the black was telling me "I'm about to come apart". I have since ordered a cutting tool with a 30 degree shoulder so I shouldn't have that problem again. I was using a threading type tool to trim the necks and that was the wrong tool to use I guess. The 30 degree tool should stop me before I cut too far . When my case started to separate, it was a nice even ring around the base not a jagged look like you have in the picture. Maybe someone with more knowledge about the subject can chime in.
Best,
Dan Batko

"Where are we going and why am I in this basket?"
 
Section some cases. Especially if you are just learning to neck turn or when you start turning a new cartridge it pays to section a few cases just to insure that you have the tool set correctly. It's great piece of mind. The razor saw is available at hobby shops.

razorsawsectionedcases.jpg

razorsawandcase.jpg
 
Load

31.2 gr of XBR, not even the hot load.......I shot 30.5 of 133 with cases turned the same way last year.
 
Bump die

I used a regular ol' neck die to bump shoulders where the bushing was doing the bump (push). Couldn't make a whole match without some necks coming off in the die. Charlie Hood made me the first and only "nek nokker" tool to drive the necks out of my die. Pretty cool little tool to cover up stupid.
 
Head space

This can also be caused by excessive head space. Do you have a way to measure how much you are bumping the shoulder back when you resize? Hope this helps: Tony
 
number of firings

My estimate is 10 to 15 firings..one thing I forgot to mention is that I tumbled those cases overnite (on accident). I usually never tumble my match cases and I wouldnt think that it could cause an issue like that. I now turn necks right to the neck/shoulder junction, I have close to 10 firings on my new match cases and so far I havent had an issue
JCK
 
Neck thickness

Another thing I forgot to mention is that I use a .269 neck and turn my cases to .0130 thickness.
 
Sizing Die & Bushing(s)

Jonathan...
What kind of sizing die are you using? Also, are you using bushings with that die, or is it a fixed neck die...???
 
Another thing I forgot to mention is that I use a .269 neck and turn my cases to .0130 thickness.

.013 on a .269 neck? If so you are at zero clearance, or less than zero if you factor in the pressure ring on the bullet.
 
Ditto...

I agree with these guys...you should be allowing at least .002" total clearance in your chamber...in other words, a loaded round should mic no bigger than .267 across the pressure ring of the bullet...
Additionally, and just as importantly, do you have the button screwed down tight in your Redding die? If so, another opportunity for bad Ju-Ju. Back the cap off 1/2-turn from locking down tight on the bushing. This will allow your bushing to "float"...and allow approximately the bottom .035" of the neck not to be sized. As your cases work harden, if you continue to stress that neck/shoulder junction where your neck-turning cut ends, you WILL continue to have separations. In 24 years, and in using sets of cases for dozens of firings, I've only ever had the problem you're describing ONE time...and that was with the first set of cases I used when I moved to the Redding Small Base PPC die, and all because I had the bushing locked down tight in the die, which caused the entire neck to be sized right down to the very junction of the shoulder. Allow it to float...that unsized .035" won't hurt a damned thing...
 
I have had this problem over the years with my 30's. I have always lain it to cutting too far into the shoulder junction but sometimes they break below where the junction is; just slightly. I keep a cleaning brush on a short rod at the bench for this eventuality. I have noticed that I have some cases that are beyond old that have lived through all the same trimming, bumping and loading that the others have. Leads me to wonder about the grain structure of the brass in the cases themselves.

I have seen folks say on here that brass does not flow and that necks do not grow but that is not what I have experienced over the past 11 years of BR. I have found that necks do grow, both in length and in thickness as one uses them. Perhaps it has something complex to do with all that has been discussed.
 
I checked my book, and I actually turn them to .0125....if that makes enough difference

Still sounds pretty tight. Probably less than .001" total clearance once a pressue ring of .0003-.0005 is factored in. Unless you are experienced in fitted necks I would back it off to .012".

What does a loaded round measure?
 
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