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Case separation.

I know this has been discussed before on a shooters web site. Can't remember which one.
Anyway I was trying out some loads for my 6mm.Rem. in model 788 rifle today. 46.5 grns. of 4831 with 85 grn. Sierra HPBT's. The second rd. fired separated about 3/8th of an inch up from the base of brass. I don't consider this a mild load but it's never showed signs of pressure in the past. But just to be safe I've dropped to 45 grns. The problem that I need help on is the case stuck in the chamber. I haven't tried anything but a cleaning rod so far, but it slides right by the lip on the neck. Any one who has experienced this before and solved the problem? Need some input. Thanks.
Dan R.
 
If it wont come out with a larger caliber brush on a chamber cleaming rod youll have to get creative. They make a tool that goes in and once past the neck it springs out and grabs but it was made for necks only and may not go in but well worth a try. If not that freeze the barrel and try again with the big brush from the back. Dont get too carried away with chisels and torches or you'll have to send it to your gunsmith anyway which is the other option
 
The load isn't what caused it. The headspace on the case is. You pushed the shoulder back too much when you sized them. Then they stretch and separate near the back. Matt
 
As dusty said remove the bolt and using a over sized copper brush push it until the tip just enters the neck and yank it back out. A little Kriol or penetrating oil works wonders and letting it sit for a while.

If you were using new brass and the case separated after a few firings then you are over resizing the case causing the case to stretch and thin and separate.

Below is an animated image of a cartridge firing and stretching to meet the bolt face, and when the head clearance or the air space between the rear of the case and the bolt face is too great the case will stretch, thin and separate.

HeadClearance_zpsf30a3af1.gif
 
dkhunt14 said:
The load isn't what caused it. The headspace on the case is. You pushed the shoulder back too much when you sized them. Then they stretch and separate near the back. Matt

Yup this is the culprit. Before I got the proper tools for setting my dies up I had a 6CM separate. I took a 7MM jag and a patch, removed be bolt, stuck the jag in and tapped the butt of the rod with my Palm a couple of times. Yanked the rod and it popped right out. Easy, peasy as 1,2,3...
 
The oversized bore brush worked like a charm. Couple yanks is all it took. I knew you guys would come up with the answer. Thanks a lot.
Sitting the shoulder too far back also makes sense as being the cause of the separation. But how do I get around that if I need to full length resize? Sometimes it seems to be the only way. 'course it might just be the quickest way. Anyway thanks again. Really appreciate the help.
Dan R.
 
Ross308 said:
Sitting the shoulder too far back also makes sense as being the cause of the separation. But how do I get around that if I need to full length resize?

Two variables - shoulder set back and case body re-sizing - that may need to be addressed by a sizing die that better matches your chamber's profile. Sometimes a particular brand of die will work well for both, other times you're better off having a custom die made (typically) from the dimensions of several cases fired two or three times with minimal sizing in between firings.

David Tubb designed a sizing die for his 6XC cartridge early on that featured bushings that incorporated neck-sizing portion as well as shoulder-contact surfaces. These bushings were available in a few select neck diameters but are to be set independent of body die depth. In this manner the two variables could be handled to best suite a given chamber.

I know Neil Jones (http://www.neiljones.com/) may still make up custom dies of a similar design - steel bushings for neck and shoulder that "float" in the body dies he builds - and I'm pretty sure other gunsmiths do also.

Question is do you need to spend upwards of $250 for a custom die if tuning your practices with off-the-shelf dies (maybe another brand than what you prefer) will effect a solution?

My experience with one particular recent cartridge development - 6HAGAR - indicates it's the brass design, not the sizing practices employed. Before Hornady made a custom run of 6HAGAR brass a couple of years ago one of two available "parent" cases for forming 6HAGAR brass was notorious for case head separations sometimes after as few as two reloadings. It has to be said that this brass was intended originally for pressures of 35,000 lbs & in the 6HAGAR it's more like 50,000 or better so there's some compromise inherent in using this brass in this manner. Used as intended the 25 Remington brass would last a long time.

With the 6HAGAR it was pretty easy seeing incipient separations on fired brass; a rough-looking stretch ring would show up about 12mm ahead of the extractor groove. I had all but one case actually separate on me during a match once in 5 seasons & that one time a 308 bore brush was the key to getting the forward part of the case out of my space gun's chamber. The head went flying out the ejection port....
 
The instructions the manufacturer sent with your FL size die probably said to screw the die down until it contacts the shell holder with the ram full up and then maybe even turn the die down another fraction of a turn from just touching. Whatever it says, if you do like the instructions say the die will push the case shoulder all the way back to minimum spec. length measured from base to shoulder datum line so it’ll freely chamber in the shortest of all factory chambers on the planet.

Best for a bolt gun is to adjust the die so it bumps back the shoulder minimally, only .001” to .002”, on a case fully fire formed in so completely filling the length of that chamber. Probably the easiest way to finely adjust the die is to initially setup the die on a regular shell holder then adjust using one of the set of Redding’s Competition Shell Holders which gets you five shell holders each .002” to .010” longer from where the base sits to the top of the holder so that much less of the case’s length gets shoved up into and sized by the die.

'Freak
 
Ross308

Look at the exaggerated blue, red and green dotted lines below, you only need to push the shoulder back .001 to .002 shorter than the red dotted line. The green line represents the die manufactures instructions for setting up the die and why you had a case head separation. The Redding’s Competition Shell Holders mentioned above are a very good and fool proof method of sizing and still have the die contact the shell holder and have the press cam over.

shouldersetback_zps59bf1b04.jpg
 
Thanks for the solutions for shoulder set back. I'll see if I can do some adjusting and tweaking and maybe make it work. The thing is the 788 shoots pretty good for what it's made for but too put a lot of money in new equip. for what I would gain might not be the best way to go. But I do have a .308 Rem. Varmiter that I know will shoot a lot better than it is at present. Maybe I can use this info. to make a one holer out of that. Thanks again.


Thanks big-Can't be any clearer than that.


Dan R.
 
Ross308 said:
The oversized bore brush worked like a charm. Couple yanks is all it took. I knew you guys would come up with the answer. Thanks a lot.
Sitting the shoulder too far back also makes sense as being the cause of the separation. But how do I get around that if I need to full length resize? Sometimes it seems to be the only way. 'course it might just be the quickest way. Anyway thanks again. Really appreciate the help.
Dan R.
Next time it happens, just run another round in behind the stuck one and give it some pressure with your hand. When you extract it, both will come out.
I went through this with a 6.5x55 years ago, didn't know it had separated, went to put another round in, bolt wouldn't close, whacked it a couple times, then withdrew the bolt to find the live round jammed into the separated case. Never did find the head.
My problem was caused by the brass manufacturer, they had sized it short on their first few runs without catching it before it hit the streets.

Cheers.
:D
 
Ross308 said:
Thanks for the solutions for shoulder set back. I'll see if I can do some adjusting and tweaking and maybe make it work. The thing is the 788 shoots pretty good for what it's made for but too put a lot of money in new equip. for what I would gain might not be the best way to go. But I do have a .308 Rem. Varmiter that I know will shoot a lot better than it is at present. Maybe I can use this info. to make a one holer out of that. Thanks again.


Thanks big-Can't be any clearer than that.


Dan R.

Adjusting the die might help a bit, but don't get your hopes up for long case life.

The Remington 788 is notorious for head separations because of the rear locking bolt lugs. Spend some time working with the 700/308 - your efforts will be better rewarded.
 
I think we go through this same topic about once or twice a year. Learning how to properly set up your Sizing die weather it be a Full Length, Body Die or Shoulder bump die is not all that well known by fellas that have been loading ammo for 20 years it seems.
I bet there is a U tube video out there that shows the correct way to do it and maybe more importantly what tools you will need to take the correct measurements so that you "Know" how much your moving your brass to make those corrections.

Glad you got that shell out. Its not a huge deal to spin the barrel off to get it out but down time kinda puts a kink in your shootin.

RussT
 
"The Remington 788 is notorious for head separations because of the rear locking bolt lugs."


More specifically, bolt compression. Over 3.5 inches of bolt ahead of the lugs allows the compression of steel from rearward thrust against the bolt face. I have read as much as .003 movement with average chamber pressures. The brass case stretches this much each time it is fired. It gets weaker with each reload and fire cycle. The above mentioned die adjustments have little effect at extending brass life when fired in a Remington 788.

I have a 7-08 bought new in 1980. The best brass life I can get with any new brass is 6-8 times fired before evidence of head separation becomes visible. I have had new brass fail in as few as four firings.

I have had plenty of cases break clean without ever seeing that bright stretch ring at loading. I made up a little brass tool to easily remove the stuck body from the chamber. Inserted using the bolt to push it to where the nose clears the case mouth. The sharp shoulder rides over the end of case. I use the pointed jag to act as a wedge to spread the "jaws", and push it out by tapping the cleaning rod it is attached to. Works every time.
 

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I "had" two Remington 788 and the problem was on the larger diameter cases and bolt thrust, the person who talked me into buying the 788 had a .222 a smaller base diameter case and didn't have a problem.

But I didn't learn anything. (Enfield humor) :o So I kept the chamber pressure below 43,000 cup. ;)

IMGP1115_zps3cb3bd3c.jpg
 
Nice collection bigedp51, with those enfields do you have a spring loaded ejector pin in the bolt face? If they don't case head separation tends to be a minimal issue since they head space off the rim. Those with a spring loaded ejector in the bolt face though would have to fallow the same rules as a regular shell that head-spaces off the shoulder.
 
The first CF rifle that I owned was a 788 in .308. I started out with a Lee Loader and a plastic mallet, loading the same cases over and over. I never had a separation or sign of one. One little piece of confusion, that seems to cloud the calculations of 788 bolt compression is the difference between bolt thrust, and chamber pressure. Cases cling to chamber walls, and that reduces bolt thrust. If you want to read more about that, I suggest PO Ackley's two volume set, volume 1. In any case, one should first arrive at a reasonable figure for thrust, and then that should be used to calculate compression, rather than using peak chamber pressure, which is significantly greater. It is very common for shooters to make mistakes in setting FL dies, and that is the reason that I believe that my cases, did not separate. They may have been tight, but there was no way to set their shoulders back, with a Lee Loader. Another thing that needs to be known is that light loads in rimless cases can actually result in shortened shoulder to head dimensions. I have tested this. It is not a book or calculated thing. The easiest way to see this is happening is that if you continue using the same light load, the primers of fired cases will protrude by increasing amounts as cases progress through several firings. I did my test with neck sizing only.
 
Grimstod said:
Nice collection bigedp51, with those enfields do you have a spring loaded ejector pin in the bolt face? If they don't case head separation tends to be a minimal issue since they head space off the rim. Those with a spring loaded ejector in the bolt face though would have to fallow the same rules as a regular shell that head-spaces off the shoulder.

The Enfield rifle does not have an ejector in the bolt face and the extractor moves to the right and away from the case as the bolt closes. This leaves the base of the case unsupported and laying in the bottom of the chamber, and American made cases tend to run on the small side in diameter.

No4bolthead003_zpsbb1d9c31.jpg


headspacestretch-c_zps8f362fcb.gif


zeroheadspace_zpsbaf7579c.jpg


Both the 788 and Enfield rifle have rear locking lugs and I never had a case head separation with either type rifle. And it doesn't matter if the cases has a rim, a belt or is rimless you can still control head clearance with the "shoulder" of the case. The quality of the brass meaning dimensions, brass hardness and your reloading technique play the biggest part in case life.

I prefer full length resizing but that is impossible on the .303 British Enfield because the military chamber was enlarged in 1914 to make room for the mud of Flanders fields and sloppily made ammunition. We had a debate about the shoulders of the cases contacting the chambers shoulder here but "some" chambers are so large that your brass get so distorted and warped that you need to iron out the case in a full length die.

In my opinion case head separations happen because the reloader follows the die makers directions which pushes the shoulder back to far and also does not have gauges to check their fired cases for minimum shoulder bump.

And BoydAllen is 100% correct above in his last post and the Enfield and 788 are not "magnum" rifles and are very good rifles when loaded correctly. ;)

P.S. And if some of those long haired commie pinko pervert benchrest shooters here owned an Enfield rifle or milsurp rifle with humongous chambers they might understand about tortured brass and full length resizing. (calm down its called humor) :D

And if your a bench rest shooter and an Engineer then read this.

hafordummies_zps135ebcb6.jpg


Bazinga!

is_ani_zps6d757ccc.gif
 
I should publish a picture of the No.4 MkI Enfield that I own. It came to me from an eccentric friend's estate. It has a number of "clever"modifications. For instance, the grip frame from a model 29 or some other large frame Smith and Wesson was welded to the trigger guard to incorporate a pistol grip in the sock design, complete with full S&W grip panels. The trigger was worked over to the point where it is actually pretty good. A home made scope mount was fabricated, that while crude, is sufficiently sturdy to provide a reliable mount. The barrel is from a No.1 Mk.4 whose bore he admired, and the tip of the forend is held in place by a stainless hose clamp, that was not trimmed after tightening. The butt has been squared off, and a piece of oak and used pad added to it. (blocking access to the stock bolt) The length of pull is a bit too long,even given my 37" sleeve length. When I was given this rifle, I decided to have its headspace checked (It was within spec.) and to see what I could do about working up a load that would give me an inch at 100 yards. What I learned in the process was that the thin brass would distort quite easily, turning into the proverbial banana if I put it through a FL die, and this did not do good things for accuracy.....so I improvised, using a .300 Savage die to neck size the brass, and with Sierra bullets of the correct diameter, working up a load carefully out of respect for the action's pressure limits, I was able to shoot a five shot group that met my 1" goal, this with a 4X scope. Some time after that I sold the dies, and the rifle went into the safe. What I really need to pick up for it is a collet die set. I think that they make them, or used to, but it has been a while since I looked.
 
BoydAllen

I sold off all my milsurp collection and only kept my best No. 1 and No.4 Enfields and with the money I bought all new rifles. BUT even with stock off the shelf factory rifles and mediocre brass the cases can warp and with a custom made rifle with a snug chamber and good brass this problem is greatly reduced. And the sizing method for these tighter chambered rifles is more practical as described by the bench rest shooters.

So with my rifles the "rat turd in the violin case" works best for me the majority of the time and for "many" people who come here wanting to load more accurate ammunition.

I was in the CMP reloading forum the other day and I asked what would they consider maximum runout on 30-06 cases measured at the neck after sizing. And they said I was being too fussy and just shoot my M1 Garand and not worry about it. :o
 

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