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Bulseyetom
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First firing after fireformind case failures
Jul 16th, 2017 at 6:36pm
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I got my rusty butt out of bed this morning and headed to the range to make more brass for my Rolling Block chambered in 6mm-30/30 Imp and to try out a few loads with the cases I formed a week or so ago. I lost 4 Hornady 25/35 cases while fireforming due to splits in the body which was about twice the loss rate of last time out.  I have ordered some Nosler 30/30 brass to try and see how they work.  Case loss while fireforming does not bother me with these thin cases but what did surprise me was that I lost two cases in the first loading due to developing a severe dimple just in the case just below the neck junction.  I have shot wildcat cartridges for years and a million standard reloads and I never recall seeing anything like this before.  I am using a universal neck sizing die and I wonder if I sized just a tad too far?  I never thought of that until I sized the cases I shot today and visually it looks like I stopped right at the junction of the neck and shoulder but what else causes such a defect?  Tom   Undecided
  
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martin 1940D28
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Re: First firing after fireformind case failures
Reply #1 - Jul 16th, 2017 at 8:31pm
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I've never seen this with neck sizing, but with full length sizing, all I can do is guess. I'm sure someone will have an answer. M
  
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Bulseyetom
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Re: First firing after fireformind case failures
Reply #2 - Jul 16th, 2017 at 8:56pm
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These cases are straight from the chamber and have not been sized since firing.  Has me buffalo'd.
  
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JLouis
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Re: First firing after fireformind case failures
Reply #3 - Jul 16th, 2017 at 9:03pm
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Strange indeed I have seen it when sizing but not from fire forming to date? By chance did you open up the necks to a nice snug scrape fit into the chamber first?

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Re: First firing after fireformind case failures
Reply #4 - Jul 16th, 2017 at 9:11pm
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Could it be bullets only seated a short distance into the cases, along with slow powder? 
This might allow gas in between the bullet that is nudged away from the mouth  and the case not yet puffed up to form a seal. 
I have seen this with fireforming loads with small necks and no bullet (gas gets in there and makes its own path)
Hope this is understandable...
  
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Bulseyetom
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Re: First firing after fireformind case failures
Reply #5 - Jul 16th, 2017 at 11:14pm
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I did not open the neck after sizing. I was using Re 17 powder with a pressure of around 38000 psi according to Quickload.  I think the bullets were seated into the neck 0.30 in a 24 caliber case.  I shot 17 rounds and this happened twice.   Lips Sealed Undecided
  
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Re: First firing after fireformind case failures
Reply #6 - Jul 16th, 2017 at 11:49pm
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Well, that's all I could come up with, Tom. Sure hope somebody comes up with a more certain answer for you.
  
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Re: First firing after fireformind case failures
Reply #7 - Jul 17th, 2017 at 1:06am
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can't see the picture real clearly with old eyes, but.
looks to be black on the shoulders, and around one of the inward bulges.
this might suggest that the shoulders at least were not fully blown out to fit the chamber.
with rimless cases this would mean a slight issue with headspace, but rimmed headspace on the rim.
if the cases are a little hard in the neck, needing annealing, and there is a gap in the shoulder area, insufficient obturation would easily let gas back onto the exterior case body.
re17 should be a good powder for this case, but will not give much pressure with light loads.
a good start might be to anneal the necks and fireform with stoutish loads to blow the shoulders to fully fit the chamber.
some annealing of the shoulder would help here.
using tempilaq will let you get the correct temp of 700 to 750 degrees.
just surmising.
keep safe,
bruce.
  
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marlinguy
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Re: First firing after fireformind case failures
Reply #8 - Jul 17th, 2017 at 9:09am
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Has the look of a load that was too light and didn't seal the chamber, so pressure slipped past the neck/shoulder and built up where the case fit and sealed well. The black soot from gunpowder at the neck and shoulder indicates some blowback where it's not sealing to me.
You mentioned the pressure is about 38,000 which seems high enough to seal well, but what is your load for these cases?
  
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Re: First firing after fireformind case failures
Reply #9 - Jul 17th, 2017 at 11:26am
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Remember, that shoulder on the 25-35 cases is Very
small/ almost a straight taper into the neck from the base.
Lots of room for powder gases to crumple the neck.
I would think a person better off to work down annealled 30-30 or even 38-55 cases so you are starting with almost fully formed shoulder area
beltfed/arnie
  
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Re: First firing after fireformind case failures
Reply #10 - Jul 17th, 2017 at 11:27am
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Oh, but one must check as to neck thickness when forming down from 30 or even 38 cal cases. May need to neck turn.
beltfed/arnie
  
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Bulseyetom
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Re: First firing after fireformind case failures
Reply #11 - Jul 17th, 2017 at 4:55pm
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The load that caused the case failures was 33.0 grains of Re-17 with an 85 grain Speer BTSP seated with the shank 0.25 into the neck.  I also had loaded 105 grain Speer over 30.0 grains of Re-17 with no problems.  I fired 10 rounds of the 85 grain load and had two failures.  I am loading some 85 grain bullets as we speak with IMR 4895 from 40,000 up to 44,000 to see how that powder works.  Next I will try IMR 3031.  Assuming that the original loads for the 1902 Rolling Block in 7x57 were loaded to 39,000 and increasing by 24% due to the smaller head of the case of the 30/30 I should be able to work up to 48,000 but I feel no need to get that high and am staying 10% lower.  Tom
  
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Re: First firing after fireformind case failures
Reply #12 - Jul 17th, 2017 at 5:35pm
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MY nickle (not much value in today's dollars) is that a slight flair at the mouth will seal it and prevent the gas leaking back around and denting it.  Of course there will be other things that work too.

  
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Re: First firing after fireformind case failures
Reply #13 - Jul 17th, 2017 at 6:15pm
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I'm probably seeing it wrong, but there may be a split on the lower case at the shoulder by the dimple. That could be how pressure is building outside of the case to dimple inward. Like others have mentioned, I'd try to form enough of a shoulder to head space off of there instead of the rim. Maybe, since it's been a problem, anneal the new brass along with checking neck thickness and uniformity when coming down from thirty cal. Best of luck with it.
  
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Re: First firing after fireformind case failures
Reply #14 - Jul 17th, 2017 at 7:23pm
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I have always fire formed with cream of wheat, a full powder charge and a wad in the mouth of the case to blow out my cases. Never had any success while trying to use a bullet to accomplish the same but just the opposite. But don't do as I do check with several others first and see what process they have used with good success. 

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