BOY do I have pressure!!!! UP DATE!!!!!

[DLH]

:shock:    I'm loading a 358 Norma mag.    The caseings that I am using are new Fire formed 338 Winchester cases by Remington.  The bullet is a 250 g by Hornady,  The primer is a fed 215 large rifle Mag. primer.  and the powder load is 69.1 g  of  IMR 4350,  by Hornady's book that is a mid range load.
    After the shot, the front half of the case looks perfect, but the back half???
  The primer is FLAT, and all of the cases have a crack above the web.

  This rifle is a rechamber from a 35 Whelen, and has been checked with  GO  - NO GO   gauges, and fount to be right on.

    If I go much lower in powder I'll have a 35 Whelen agian!!

Thanks

[jhalcott]

So what is wrong with a WHELEN????I love mine!!
   first ,are the cases new or old? Can you get a chamber cast and measure the cases?. Most important,can you get some chronograph readings of this load.Just because the book shows a midline load,your gun might be a faster gun then what the book used. Did you start at the  lowest charge and work up?Another important question is how did the gun react with factory loads.My Whelen has a chamber cut to use resized 30-06 brass.This is about .020 SHORTER than factory ammo. PRESSURES WILL SKY ROCKET IF i DO NOT TRIM FACTORY BRASS.Borrow a chronograph And see how fast you are pushing those bullets for real.It might be an eye opener.
  I use a "mid line" load of 4320 in my Whelen and get OVER 2700fps with 200 gr hornady's.The gun is a rebarreled Mauser. Trimmed and reloaded factory brass using factory components show pressure signs.
  Hope this helps ,jh

[Blackhawk44]

Have a gunsmith (not a parts changer) cast that chamber and throat and measure it to be sure that everything was truly cut to design spec.  Especially watch that throat since its a rechamber.  One step at a time.

[Rick Teal]

I think you must have a chamber problem.

My .358 Norma is a bit unusual.  I had it built for testing bullets (I swage) at high velocity.  It's built on a 98 Mauser action, and has a 27 inch bull barrel, with a 1:12 twist.  

I know my numbers can't relate directly to your gun and loads, but here they are for your information.  So far, I've only used resized Norma brass.  My shooting has also been in the summer.

It shoots 225 grain Ballistic tips at 3060 fps and my own 220 grain bullets at 3260 fps (softer jackets, longer shanks) both using 79 grains of IMR 4350.

When I load my own 245 grain bullets, I've been using 73.5 grains of H4350 (should be fairly close to the IMR burn rate), and I've been getting 2825 fps.

In both cases, I've been getting very minimal pressure signs.  Only a slight flattening of the primers.  Nothing I would even look at twice in any of my other rifles.

[Toolpush]

Please don't take offense but what I'm reading tells me that your cases are stretching alot. I would suggest checking the dies adjustment and see if your pushing the shoulders back too far. If that proves to be fine I'd index a few to see if they crack on the same side of the chamber each time.  This might show one lug holding most of the pressure.

You didn't say how close to the lands you are seating  the bullets. If the bullets are jammed in the lands pressure will climb a lot faster than normal.

Another thing just dawned on me is that  the bolt face had to be opened up to accept the Norma. Could it be that it wasn't cut square? Indexing would show this also.

How much is the brass growing? Was it short enough to begain with.

Who's action is it? Is it prone to stretching? Is the increased blot thrust causing this problem?

Like I said on the onset "Please don't take offense" these were some things I'd look at.  A chamber cast might be money well spent.

[Blackhawk44]

In re-reading your post- are the cracks around the circumference or are they longitudinal?  Still need that chamber cast.  If crack is about the circumference, like Toolpush said, likely a die problem.  If lengthwise cracks, possible oversized chamber (in diameter).  The headspace gauges could fit correctly and you could still have a chamber issue because the guages are only measuring a length, not the diameter.

[DLH]

:shock:   I will be working  (checking)  On this gun this weekend, sounds like a long weekend!!!!
   The bolt face  is a place that I hadn't even thought of!!

Thanks to every one

DLH

[Toolpush]

Be sure and let us in on what you come up with.

[DLH]

Well the first step,  I checked the bolt face, SUPRISE!!!    where they opened up the face,  they did not take it down to the level that the orignal face was.   There is a ring all the way around the bolt face .010"  high. The ring holds  about  .025" of the rim all the way around.
    I turned the face true. I know that will affect the headspaceing, so I will rent the reamer and Go, NO GO gauges, and set the barrel back, and rechamber it.
  I guess if you want it done right you gotta do it your self!!!!

Thanks  :x

[The Shrink]

DLH

Just thinking through your options, I would suggest at least a chamber cast before you cut anything.  Check the bolt lugs to see if they engage, and how fully.  Investigate bolt stretch.  

Basically I'm suggesting you do a full diagnostic workup before you change anything, and then take a look at the whole problem.  If they did that sloppy a job on the bolt face, who knows what else is wrong.  I'd not be comfortable with any assumptions about this rifle knowing what you now know.

[EDG]

This sounds like your primers are back out due to excess head space. When the case backs up due to the case pressure over coming the pressure in the primer pocket the head nearly separates.  You can find really flat primers in once fire .303 British ammo due to the same problem.
If I had a .358 NM I would set the chamber to head space off of the shoulder of your loaded ammo plus .003"  and not off of the belt. Then cut the belt recess to the depth of the longest belts in your lot of brass.  Yeah this will not allow you to shoot factory .358 Norma ammo but no one can afford it anyway.
Whoever checked your headspace might have made a mistake.
Ed

[DES]

DLH,
I had a Rem 721 rebarreled to .358 NM and used .338 Mag brass also. You didn't mention how you fire-formed but I found that I had to seat the bullet out to touch the lands (to fire-form) or I got some case seperation when firing again.  I could see the 'step' on your boltface affecting how the primer looks but not sure that alone would cause the case to seperate.

[DLH]

:shock:    Well I recived the reamer and the GO,  NO GO gauges. after I trued up the bolt face ( removing a max of .010" of metal)  I found that the NO GO gauge would fit as a matter of fact I crazy glued 2 pieces of .030" shim stock to the bolt face, and the NO GAUGE still closed!!!  snug!  but it closed!!!!!
   Sooooooo  I set the barrel back 1 full turn , and recut the chamber!!  ( boy the barrel is free floated now)    Yesterday I went to the range with my press an proceeded to reload.  NO pressure!!  No cracked cases!  and I went clear to the top of the reloading book.

      I wish that I knew who did the chamber job, I would advise him to take up knitting so that he would be the only one in DANGER!!

      Oh yea!   that sucker kicks!!!   why did I ever want one so damn big???

Thanks

[The Shrink]

Yes, I agree about the knitting. But I don't think I want to wear the socks he makes, either!  

Your last question opens up a whole nother topic!  Planning an Alaska trup anytime soon?  Africa, maybe?

[DLH]

Not Africa.  Too Hot!!   But now Alaska???   Thats always on my mind!!!!