10mm reloading case failure. What could cause this?

stevew20

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I was testing some new 10mm reloads this morning and one of the cases sheered in half. This is my first time reloading 10mm and I’ve heard it can be sensitive to pressure spikes so better to be safe than sorry. Any help diagnosing is appreciated...
case - 1.jpeg

I’ve reloaded over 30,000 rounds of 9mm, 45 ACP, 380 and 38 Special and have never had a case failure like this, even after loading some brass 10-20 times. This was a once fired piece of Sig Sauer factory brass.

My loads were light compared to factory 10mm rounds. I had worked up loads between 5.6 and 6.4 grains of HP-38. According to my manuals (start 5.9 - max 6.6), this range should only produce between 1,000-1,100 fps. The cartridge that failed was loaded with 6.0. Note, the Sig factory ammo I shoot is 1,250 fps.

Couple of possible culprits, maybe?
  • Due to the primer shortage I was using magnum primers, which is why I started with loads at the light end of the spectrum. Could a magnum primer cause a spike in pressure without creating a corresponding increase in velocity?
  • My OAL was below optimal. I was at 1.235 whereas the manuals I have a OAL range between 1.250 and 1.260.
I guess it could have been a double charge but I’m a careful reloader and have never had one (that I know of). And the recoil on this round wasn’t anything noticeable different than the one before or after.
  • Brass: Sig Sauer. Fired once. Large primer pocket.
  • Bullet: X-Treme 180 grain RNFP
  • Primer: CCI Magnum Large Pistol (350)
  • Powder: Hodgdon HP-38
  • OAL: 1.235 (range in manuals is between 1.250 and 1.260)
  • Press: Dillon Square Deal B
  • Pistol: Springfield TRP 1911 10mm
I used just a bit of crimp. Cartridge on the left is a factory Sig round, reload on right. If you look closely at the pulled bullet, you can see a slight indent from the pullet seating and crimp.
case - 3.jpeg

Primers look a little flat but okay to me…? Brass on the left is a factory Sig round. The others are my reloads, all with same powder charge.
case - 2.jpeg
 
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jpm

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Seating the bullet deeper will raise the pressure and the magnum primer on top of that will raise it even further.
 

jpm

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btw I reload 10mm too with the same bullets and the same powder as well as blue dot and one other and I've not seen a case separate with that yet.
 

Mountain

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I do not know about this particular powder, but some powders have problems when loaded below minimums. You can get pressure spikes / detonation. Unless a powder has a well known and published history of performing safely for light loads, the 'minimum' is not a suggestion.

Your slightly short OAL's and magnum primers alone would not split the case like that. That primer definitely looks flatter than your others and the factory load especially. Do your reload cases show the belly bulge where unsupported by the chamber? FWIW, I've reloaded Sig cases a few times and have had zero problems with loads on the hotter side- not above max load but certainly full power loads.

My bet would be on a double charge or an excessively light charge detonating. Another possibility is that your scale is off and you were overloading without realizing it.
 

jpm

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It does look like it split around the same place the bullet base would have ended up when it was loaded to me. So light charge detonation could make a bit more sense I think if it was a light charge, but I think he said this was a 6.0gr charge.
 

stevew20

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Thanks for the replies so far. I appreciate it. Couple of follow-up to questions asked.

I mispoke in my original post about min/max ranges.
  • The Hodgdon website lists min and max range between 5.2 (944 fps) and 5.8 (1061 fps).
  • Lyman and Nosler have ranges between 5.9 (1037 fps) and 6.6 (1125 fps.
I decided to go in between these two differing set of ranges with 5.6 - 6.4. The cartridge that failed was at 6.0. So according to Hodgdon it would be 0.2 over max. But for Lyman/Nosler it would be just 0.1 over minimum.

Quite a few comments about the combination of a magnum primers and min powder possibly causing detonation. I hadn't thought of that. Using magnum primers is probably a bad call for this particular cartridge. I think I'll save them for something else.

Mountain, no, not seeing any bulges where chamber is unsupportive. I also double checked my scale against a second scale I have when I got home and it was okay.
 
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stevew20

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jpm, this is where the split happened.

case - 4.jpeg

It does look like it split around the same place the bullet base would have ended up when it was loaded to me. So light charge detonation could make a bit more sense I think if it was a light charge, but I think he said this was a 6.0gr charge.
 

TrashcanDan

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Hodgdon site call for win large, and win large is both a standard and mag primer. I use em in .45 all the time, never had an issue. Primers aren't pierced or pushed out, so its not a huge pressure spike, I could also be reading them wrong.

Thats a decent charge of fast powder. I'm using less that that for .45 and loading to almost the same o.a.l. as you, so stretch it out some (mag's going to dictate your max o.a.l.) and go with something slower burning like Blue Dot or 800X. I'll add a link to burn charts.

Hodgdon site also says 34,900 for 5.8 grs of HP 38/ WIN 231, so whats your other manual list for 6 and up?

Ditch the crimp, that'll cause a spike. Back off on the die and put calipers to it. You want sammi spec plus the difference of plated, so..............spec+.001? That'll be in a manual, casemouth dia.

Looks like it separated right at the base of the projo

 

jpm

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@stevew20 By chance is the Lyman/Nosler data you're quoting for a jacketed bullet? That's what it sounds like. My notes show I use between 5.2-5.5 of that powder with that bullet.
 

stevew20

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TrashcanDan,
  • Lyman (49th edition) shows 180 jacketed HP with Win 231 at 5.9 = 1037 velocity and 26,300 pressure. Primer is CCI LP.
  • Hodgdonreloading.com shows 180 jacketed HC with Win 231 at 5.8 = 1061 velocity and 34,900 pressure. Primer is Winchester LP.
These are two very different pressures for very similiar loads between Lyman and Hodgdon.

Hodgdon site also says 34,900 for 5.8 grs of HP 38/ WIN 231, so whats your other manual list for 6 and up?
 

stevew20

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jpm, yes, jacketed hp. Do you know what the source of your notes are?

By chance is the Lyman/Nosler data you're quoting for a jacketed bullet? That's what it sounds like. My notes show I use between 5.2-5.5 of that powder with that bullet.
 

jpm

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I just checked and you're using data for Jacketed hollow points and hollow core bullets (pretty much same bullets, different nomenclature) which is pretty different from FMJ plated.

I used the Hodgdon load data and started at the low end of their jacketed and worked my way up. My notes say 5.6gr and 5.7gr with your bullet and using Winchester LPP were good loads and I seated to 1.260" depth.
 

TrashcanDan

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What problems have you had? In .223 for high power, CMP, etc. I prefer Norma, Sig, Lake City- in that order. Never had a problem with Sig brass in 10mm nor .40. Just asking so I know what to watch for.

.38 and .45

Primers. Either didn't feel right going in or went in sideways.
.45's would set 230's a little off center.
Its one of those headstamps I just toss out when I get em.
 

TrashcanDan

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What problems have you had? In .223 for high power, CMP, etc. I prefer Norma, Sig, Lake City- in that order. Never had a problem with Sig brass in 10mm nor .40. Just asking so I know what to watch for.

Could have been my tree-trunk like brutish arms too.............
These pythons don't know when to quit!
 

andrew1220

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That's the problem, you're loading too hot for plated bullets. You need to be using the low end of jacketed flat points loads. Or cast load data.
But don’t plated bullets have less resistance in the bore than jacketed? I’d think he would have some very high velocities but not a case failure/pressure spike??
I’ve inhaled too much Kroil fumes today so I may be overlooking something....
 

jpm

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But don’t plated bullets have less resistance in the bore than jacketed? I’d think he would have some very high velocities but not a case failure/pressure spike??
I’ve inhaled too much Kroil fumes today so I may be overlooking something....

They would be slightly more slippery but there's still going to have to be that initial spike of pressure to drive it out of the case and down the bore and start it spinning.

It still could just be a bad case too.
 

EddieCoyle

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Pistol cartridges don't "detonate", and no cartridge would with a fast powder like HP38. You have too much crimp and you're seating too deep. That still shouldn't cause a split like that.

Are you running a Lee FCD by chance?
 
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drgrant

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HP38 is a completely horrible powder to load 10mm with. 10mm is not for mouse farts. You should be using something with JUICE like Power Pistol, or similar, and swinging for the fences.

ETA: This likely isn't the primary source of your woes, though.... but it ain't helping anything.
 

EddieCoyle

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That's bizarre! I've never seen a case like that before, wtf? Is that to prevent them seating it too deep?
I can only assume it's a setback prevention feature. There are a few 9mm headstamps with it (all made by the same company). The problem is you have significantly reduced volume, which causes higher pressure, and the sharp corner is a stress point which causes the case to fracture when you reload it and shoot it. I sort them out.
 

andrew1220

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I can only assume it's a setback prevention feature. There are a few 9mm headstamps with it (all made by the same company). The problem is you have significantly reduced volume, which causes higher pressure, and the sharp corner is a stress point which causes the case to fracture when you reload it and shoot it. I sort them out.
That's bizarre! I've never seen a case like that before, wtf? Is that to prevent them seating it too deep?
Yup there’s a few to watch out for. After loading tens of thousands of rounds of 9mm, I’ve learned which headstamps have it. Tulabrass maxtech, FM (freedom munitions), Xtreme, IMI (Or IMT?) to name a few.
 

andrew1220

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HP38 is a completely horrible powder to load 10mm with. 10mm is not for mouse farts. You should be using something with JUICE like Power Pistol, or similar, and swinging for the fences.

ETA: This likely isn't the primary source of your woes, though.... but it ain't helping anything.
This. It’s like guys using titegroup to load 357 magnum. Yes you can do it but the performance blows and the risk of double charging is higher.

OP, if you’re on the north shore I can sell you a sealed pound of Power Pistol. That would be a great powder for 10mm.
 

meh

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Could be a one-off thing. I had one of these in factory-loaded Fiocchi 357 magnum. Happened in a Rossi, which has a slightly oversized chamber towards the back, but to date it's the only round of any kind shot out of that firearm that has failed that way. So I blame the brass on that one.
 

stevew20

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I appreciate everybody's comments. Thanks.

@EddieCoyle, no, not using a Lee FCD. Its a Dillon SDB with its proprietary dies. And no intenal sholuder like the MAXXtech shitty brass has.

I realize I was not using an optimal mix of primer (large magnum) or powder (HP38) for 10mm. I just had a free afternoon and was trying to experiment with what I had on hand to load something to shoot besides 9mm while my inventory of SPP dwindles...

I also loaded some up using HS-6. Which again, may not be ideal, but may be better than HP38 since it is slower.

@andrew1220, thanks for the offer for PowerPistol. I think I can locate some on my own but may take you up on your offer if not. BlueDot and 800x has also been recommended.

Maybe it was the perfect storm of individual minor infractions - crimp, seating depth, magnum primer, fast powder - combining to become something major. Or could be a fluke I guess. The one that failed was in the middle of my workup. I would think the ones loaded even hotter would have shown signs of failure as well but they didn't.
 
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