Separated case, odd neck dents

[vegas]

Hey everyone,

Had this case separate today. Caliber was 7mm REM Mag, no pressure signs on the primer, heavy bolt lift though. It came out no issues with pistol cleaning rod and brush. Was surprised to see those dents though. Like the brass got sucked in. Shined a flashlight in the chamber and nothing unusual other than it needs a clean. So what gives?

Thanks in advance for your help!

 

[1911nut]

Gases going around the outside of the case, hits the shoulder then needs the dents to get out the barrel.

 

[vegas]

Gases going around the outside of the case, hits the shoulder then needs the dents to get out the barrel.

Thanks. Makes perfect sense. Gases escaping from the separation.

 

[Forum Boss]

Please be careful. Read this article.

Incipient Case-Head Separation — How to Detect the Problem « Daily Bulletin

We are re-publishing this article at the request of Forum members who found the information very valuable. If you haven’t read this Safety Tip before, take a moment to learn how you can inspect your fired brass to determine if there may be a potential for case separation. A case separation can...

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Learn how to size cases properly and do not fire brass in chambers that have excess headspace.

 

[vegas]

Thanks. Will take a look to see if there is something I am missing.

For reference, brass was Hornady on its third firing. Unless something got changed with the die inadvertently, shoulders were bumped 2 thou in a FL die. Load was 180gr ELD-M going just under 2900 last time it was chrono'd in similar temps. Elevation is about 3200 ASL.

Rifle is a factory Remington 700 Long Range, 26". No prior issues in 750 rounds before today.

 

[pdhntr]

Hey everyone,

Had this case separate today. Caliber was 7mm REM Mag, no pressure signs on the primer, heavy bolt lift though. It came out no issues with pistol cleaning rod and brush. Was surprised to see those dents though. Like the brass got sucked in. Shined a flashlight in the chamber and nothing unusual other than it needs a clean. So what gives?

Thanks in advance for your help!

If you are already doing the following, disregard my post.

From new brass I try to get the shoulder blown forward as soon as possible. Depending on the load and chamber, it can be problematic. The goal is to get belted magnums to headspace on the shoulder instead of the belt.

If you can achieve this, then size the case only enough to push the shoulder back the least bit to allow chambering.

If the rifle is used for hunting, especially for dangerous game, I don't reload a case more than once and toss it after that.

I have tried the paper clip and was less than satisfied with the feedback I got from it. I use the tail of a chain saw file bent to a 90 degree hook and sharpened. The stiffer file works much better for me.

Jim

 

[pdhntr]

Thanks. Will take a look to see if there is something I am missing.

For reference, brass was Hornady on its third firing. Unless something got changed with the die inadvertently, shoulders were bumped 2 thou in a FL die. Load was 180gr ELD-M going just under 2900 last time it was chrono'd in similar temps. Elevation is about 3200 ASL.

Rifle is a factory Remington 700 Long Range, 26". No prior issues in 750 rounds before today.

No prior issues with 750 rounds, you're doing well.

Disregard my post. In my experience, some of them go right away with no explanation. With a track record such as you've had, I wouldn't be overly concerned, but if you weren't checking, that should be done.

Jim

 

[vegas]

I do headspace on the shoulder and had 6 firings on one small batch of 50 Hornady cases. So this one caught me by surprise. As I previously mentioned, the chamber does need a clean; can this contribute to headspace issues? My next step is to inspect the rest of the cases and check my sizing die and the amount it is bumping.

 

[pdhntr]

I do headspace on the shoulder and had 6 firings on one small batch of 50 Hornady cases. So this one caught me by surprise. As I previously mentioned, the chamber does need a clean; can this contribute to headspace issues? My next step is to inspect the rest of the cases and check my sizing die and the amount it is bumping.

Hi Vegas,

If you are getting 6 firings, in my opinion you are doing well.

I'm sure there are reloaders that have 10 or 20 firings on their cases and will soon be here to tell me how wrong I am, but I have never been able to get to the numbers I do with non belted cases. In my 22-250s I am getting 10 firings with no problems at all.

I have a 300 WinMag prairie dog gun and my brother has a 7mm Mag pd gun that I load for. After the second firing on the cases, I am checking each one for separation. Some go early, some seem to last up to 10 firings with no problems or hint of separation.

That has been my experience.

As far as your chamber is concerned, I guess it would depend largely on how dirty it is, and what you define as "dirt".

Jim

 

[Texas10]

Dent's in the case wall like seen in your photo usually are caused by low starting pressure not expanding the neck to a tight fit on the chamber. Gas blows by the neck, but gets stopped by the case wall further back that is sealed against the chamber wall. It then compresses the case wall as pressure falls but the neck is now fully expanded to a tight fit.

My first question is why does your photo seem to show a steel case? Is it just a photographic anomaly, or are you doing something to the brass that tarnishes it?

Are you annealing your cases? Are you overworking the cases during sizing? And finally, are you trimming your cases for proper length?

IMOP case wall dents coupled with incipient separation is an odd combination suggesting many ills.

 

[K22]

I will defer to those who shoot and load belted magnum cartridges for specifics. I know most set their dies so the case head spaces on the shoulder. The classic .001 to .002 set back may be too much for your rifle.

Surprise that the case didn't show incipient failure first, i.e. a line just ahead of the web area. I've only ever seen two head separations and both were partial, one was on a 300 Win Mag and the other on a 243 being shot in a break open TC contender which the shooter over sized the cases. The headspace on the TC was on the high side.

If you're not doing it, you should inspect each case after every firing for incipient head separation. The "paper clip" method can be tried but I wonder how effective it is at predicting incipient separation. A faint line ahead of the web is a sure indicator that the case should be scrapped.

This is obviously a serious issue and should be investigate thoroughly. What got my attention was the complete all at once failure - usually there will be a indication that the case is stretched too far before complete failure. However being that this a magnum and high pressure cartridge maybe they fail that way; I don't.

Personally I would use anymore cases in that lot or size anymore until I have the rifle inspected by a competent rifle smith and take some fired cases with me for him to examine.

 

[6MMsteve]

A bore scope is very good at identifying the thin area in the case wall...best way is to cut the case besides the file or clip method...if you headspace the barrel tight it eliminates part of this, but good sound case structure. 35 deg shoulders or more and good quality brass plays also, I think

 

[vegas]

Hi Vegas,

If you are getting 6 firings, in my opinion you are doing well.

As far as your chamber is concerned, I guess it would depend largely on how dirty it is, and what you define as "dirt".

Jim

It’s pretty filthy tbh. I shoot suppressed with this gun so it gets a little dirtier I would guess than without a suppressor. I recall reading about brass life when I first started loading for it and decided I wasn’t going to push the envelope too far. Also knowing Hornady brass isn’t the greatest was a factor too. I typically load 162’s around 3k and 180’s as noted above, just under 2900.

@Texas10 It is a photographic anomaly. I was using an LED flash light to illuminate hence the blue color tint. No annealing on these (although I did just receive an Annealeez recently), Bumping 2 thou so not going crazy but it’s always possible that the die could have been disturbed? I won’t be able to confirm this as I was loading on a Lee Turret press which was recently sold. My dies will now be living in a Redding single stage. I trim with a World’s Finest Trimmer as appropriate.

@K22 I am interested in learning more about your statement that bumping 1 or 2 thou might be too much? What are the technicals on this? I’m kind of an Occam’s Razor type of person which leads me to think that as I have had no prior issues, especially with the first batch of brass, that a weaker batch of brass is the issue. I don’t recall seeing any faint lines previously but always possible I missed it. In all likelihood, this brass is going in the trash regardless.

Thanks for the input gents. Always keen to learn because what you don’t know, you don’t know.

 

[K22]

@K22 I am interested in learning more about your statement that bumping 1 or 2 thou might be too much? What are the technicals on this? I’m kind of an Occam’s Razor type of person which leads me to think that as I have had no prior issues, especially with the first batch of brass, that a weaker batch of brass is the issue. I don’t recall seeing any faint lines previously but always possible I missed it. In all likelihood, this brass is going in the trash regardless.

Thanks for the input gents. Always keen to learn because what you don’t know, you don’t know.

The somewhat standard procedure for setting up a FL die is to adjust it so that you obtain a .001 to .002" shoulder set back from an un-sized fired case in the specific rifle that the case is being sized for. In most rifles this produces an optimum fit, i.e. easy chambering without over sizing the case. I go one step further and check the case in the rifle to make sure I've achieved this desire objective.

The FL die could be set to produce near zero shoulder set back which is what a neck sizing die does. But the FL die also sizes the diameter of the case thus increases the ability to promote easier chambering. With zero shoulder set back the case should fit the chamber and minimize working the case. Again, the case can should be checked in the chamber to verify fit.

When setting for zero shoulder set back, the FL needs to be set so the die contacts the shoulder to prevent the case from lengthening due to squeezing it thus extruding it. The bump gauge and caliber can be used to verify a die setting that will not extrude the case and yield minimum shoulder set back. Again, the case should be checked in the chamber to verify fit.

You may want to go on the Redding-reloading.com web site and read the article by Todd Spotti entitled "Dealing with Headspace" which provides perhaps better information on this issue.

However in the situation you described in your post something else may be going on besides a sizing issue. That's why I suggested that you have competent rifle smith examine the rifle.