We have seperation!

[padd54]

I was doing some fire-forming with my Marlin 62 in .256WM this morning. The loads were just above minimum set in the Hodgen Book. This happened to only one case out of 50. The case ejected and came apart in the air.

Any ideas??

 

[243winxb]

Headspacing-fire forming

Headspacing is the cause , when sizing the brass or oversize chamber (long) http://www.brownells.com/.aspx/lid=11470/guntechdetail/Gauging_Success___Minimum_Headspace_and_Maximum_COL When fire forming brass from 357mag., the stretching happens as brass forms to the chamber. The separation can happen in the body like yours or more common near the head. Sometimes seating the bullet long into the rifling can help or putting light oil on the brass so it can not grab the chamber walls. Separations can happen anytime the shoulder is pushed back to far, causing excessive cartridge headspace.

 

[Walkalong]

Shoulder was too far back when you fire formed and the bullet was not seated long enough with enough neck tension or both.

Oil might help, but I am not keen on that method.

When the firing pin hits the primer it will push the case all the way forward until something stops it. This can be a bullet with good neck tension set into the lands, or it can be a partially formed shoulder, but if nothing stops it and there is excessive headspace from not being formed fully, the front part of the brass will grab the case walls and the back part will stretch until it is stopped by the bolt face, creating a thin spot, or in this case, a separation.

 

[W.E.G.]

What case gage are you using?

 

[243winxb]

Headspace is set on the rim, but the shoulder can be pushed back to far. Or does a Marlin 62 not use the rim to headspace?

 

[padd54]

Thanks for the replys. I used the Redding 3-stage dies to form the cases, I may not of had enough neck tension on that one, but it is odd that this was the only case to seperate. What can I look for on the other cases to see if they were weakend? This case did grab a little during ejection. It was about in the middle of pack.

 

[243winxb]

Separation, if starting will look like a thin bright shiny ring. Here is a photo of a 223. More photos here > http://www.photobucket.com/joe1944usa

 

[padd54]

So, should I put amonia on my cases to make these lines visible?

WEG, you asked what gage I am using, what do you mean?

 

[243winxb]

So, should I put amonia on my cases to make these lines visible?

NO That was a different test. Ammonia should NEVER come in contact with cartridge brass.

 

[243winxb]

Here is a gage link http://www.lewilson.com/casegage.html

 

[padd54]

Thanks for the link, I never would of imagined that they made one for the .256WM.

 

[Walkalong]

Headspace is set on the rim,

True, wasn't thinking.

Wonder how the headspace in his chamber is? Still works the same. The case is pushed forward and stretches back, but it should be limited to how much built in headspace his chamber has.

 

[Innovative]

Measure your chamber clearance at the shoulder ...

Headspace on the rim is set by the firearms manufacturer when attaching the barrel. It's a very easy job for them to get right.

However, the main reason for headspace separation is too much chamber clearance at the shoulder. Handloaders need to consider this, take some measurements and minimise case stretching.

- Innovative

 

[ReloaderFred]

When fire forming cases from one caliber to another, I normally use Red Dot powder and corn meal. With experimentation, you'll get a perfectly formed case and you don't waste a bullet doing it.

I would just run them through the Redding forming die, then load a few grains of Red Dot and pack in some corn meal, making it just firm enough that it won't run out. Then point the muzzle in the air and pull the trigger. (But not in your garage, at the range)

Hope this helps.

Fred

 

[padd54]

Is there an equilent to Red-Dot? I don't have any of that. I read that you should use a normal if not near max charge during forming to ensure full expansion.

 

[ReloaderFred]

You can use IMR 700X or Bullseye for case forming. With a case as small as the .357 Magnum/.256 WM, I would start with about 5 or 6 grains and see what kind of results you get. If the case doesn't blow out all the way with that charge, them you can move it up in small increments. I use about 12 to 13 grains for blowing out 8x57 brass, so you won't want to use that much for such a small case.

Hope this helps.

Fred

 

[243winxb]

Case Forming Dies.

When sizing 7mm TCU , i could not have the FL sizer hitting the shell holder. If adjusted in the normal manner, the shoulder was pushed back way to much. Case forming dies usually need to be made to smaller internal dimensions to compensate for more spring back, because the case dimensions are being altered to a greater degree. Different brands, different specification i would guess.

 

[padd54]

I just measured the headspace of the fired cases and the ones that have not been fired. There is a .006-.009" difference. Is this excessive?
The final F/L die barely touching the shell holder. The instructions say to set the die on the shell holder up to 1/4 turn past.

I want to try annealing, do you do this before resizing or after?

 

[Innovative]

padd54 ..........

For accurate reloading, forget the instructions that came with your die. Your reading is way too excessive if you intend to get long life from your brass. How did you measure your headspace?

- Innovative

 

[ReloaderFred]

The shoulder is being set back too far in the die, so back out the die a turn or so. Getting .006" to .009" of setback is excessive and will cause separation.

I had the same problem when first sizing 10mm brass to 9x25 Dillon. I set the shoulder back too far and the brass came apart with the first firing. You have to set up the die to match your chamber.

I think the solution would be for you to send me your rifle and I'll experiment with it for a couple of years and then try to remember to send it back to you. No thanks required, just my offer to help out..........

You anneal before sizing. The annealing makes the brass soft, but it shouldn't really be necessary for this conversion.

Hope this helps.

Fred

 

[fguffey]

Sizing and forming has become an accidental art form, your forming dies, press, shell holder and cases, you are in charge, the die has threads, the press has threads, that makes it possible to adjust them. When you started you should have used new, store bought, never been fired cases, when you started the case did not have a shoulder until you formed one, the one task that reloaders can not do is move a shoulder forward without firing the case in a chamber, wildcatters can place the shoulder anywhere they choose to by finding a case with a shoulder forward of where they want it, then with the adjustable die/press they adjust both and stop just before the case is too short from the head of the case to the shoulder.

And I am not a big fan of screwing with it until it fits or is done correctly because those methods and techniques require the reloader to start over the next day as though it is a new day and careful, read the instructions before you are told you need another tool, if you take advantage of the adjustable features of the press you can make gages, size the case a little, attempt to chamber, if it chambers you have already gone too far, start over, if the case will not chamber, make a guesstimate of an adjustment, size a case and try to chamber the case again, OR get a companion tool to the press, a feeler gage and take all of the guess work out of adjusting the die to the shell holder by adjusting the gap in thoousands, that way tomorrow will not be a new day and starting over will not bew required.

F. Guffey

 

[padd54]

Innovative; I used the Hornady Headspace Gage with the "A" used. It lands on the shoulder. I measured 10 cases and got a very consistant reading on the once fired cases, the formed cases were fairly consistant, = or - .002".

I actually had to resize these as they would not chamber. Now that I have fire-formed cases, setting up the F/L die should be much easier.

This is the cartridge that I followed the manufacturers directions completly, I have never done this before.

Reload Fred; Thanks for the offer, but I will pass at this time. You are welcome to come over and assist me. I was going to anneal after fire-forming since the brass has been worked so much.

Guffey; I did use new .357mag cases. I will head your advise and lock the die down once I get it adjusted properly, I am using the Lee Classic Turret so that I can leave it in the turret.

Thanks again for all the good advice.

 

[fguffey]

"I just measured the head space of the fired cases and the ones that have not been fired. There is a .006-.009" difference. Is this excessive?
The final F/L die barely touching the shell holder. The instructions say to set the die on the shell holder up to 1/4 turn past" you are forming the case, form the shoulder to off set the effect the chamber has on head space, I do not know what method you are using to measure case length from the head of the case ti's shoulder, if the difference is .009, yes, that is too much, with practice you can size cases with the .006 to .008 thousands added to the length of the case before firing.

measure cases and the before and after measurement? I off set the effect the chamber will have on the case when fired, I form the case to fit the chamber as in form first then fire everyone else fires then determines the effect the chamber had on the case, I form first, others size then fire to form. My way cuts down on all that case travel between the head of the case and body, that is just about where your case separated.

I secure the die to the press with the lock ring, I do not secure the lock ring to the die.

F. Guffey

 

[243winxb]

There is a .006-.009" difference. Is this excessive?

Less is better. Over .010" and there is a very good chance you will have separations. But you are fire forming, the brass has to go in the chamber. You anneal before sizing. as Fred said. But not sure i would. Very short case, i guess if head is in water you should be ok. Never want to over heat the web area. Here, Fred knows best.

 

[fguffey]

.009 thousands is no go gage size for a 30/06 chamber, your cases are pinned to the rear by the rim so there is none of that stuff about the hammer/firing pin hitting the primer and driving the case forward etc. etc., the 357 case was not designed to be fire formed by blowing the case forward as in a bottle neck case, again when you form the case do not move the shoulder back more than necessary, practice, learn when to QUIT when the case FITS.

Did someone say grease the case? The case is pinned to the rear with the rim. the case body is being blown forward. I know it sound cute when taking a wild 'A' guess when selecting powder, but consider this, fast burning powder is sudden shock, if consideration to what is happening to the case under those considerations the case is not given time to think about it, it is all of a sudden, nothing then BG! slower powder goes BAANG this gives the case more time to form.

Again, form first then fire and eliminate all that case travel and remember, the techniques you are using could be damaging the cases...even though the case did not separate.

F. Guffey