First firing showing signs of over pressure?

[0.1 Aggregate]

If you were sufficiently overpressure to enbiggen the rim, I think you'd notice other signs.

. . . like full case separations, leaking primers, gas cut bolt face, and the smell of fire and brimstone.

Absolutely not accurate. High pressure can definately cause case head expansion by compressing the case head against the bolt face. With no place to go the brass expands outwards, increasing the diameter. Most reloading manuals mention this, and it is certainly not always accompanied by blown primers etc. BTW, case head separations are caused by excessive headspace, not by excessive pressures.




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[butchlambert]

Most blanked primers are not caused by over pressure.

 

[Bill Norris]

I had the same problem a long time ago, I tried a different shell holder....problem solved!

I had 1 piece of new virgin brass out of 100 about a year ago that would not go in my shell holder. I tried a different shell holder and it went in it.

 

[edwardware]

High pressure can definately cause case head expansion by compressing the case head against the bolt face. With no place to go the brass expands outwards, increasing the diameter. Most reloading manuals mention this, and it is certainly not always accompanied by blown primers etc. BTW, case head separations are caused by excessive headspace, not by excessive pressures.

Several points here:
- case head expansion is not the subject of this discussion, since it's rarely sufficient to cause interference with the shell holder; there's hundredths of clearance there. We're talking about rim expansion.
- head separation can certainly be caused by overpressure less than required to shear the lugs, although the pressure required will vary by action. The brass simply expands into the joint between the front of the bolt and the rear of the chamber, and ruptures there.

Nothing in the OP's description points to high pressure, rather it seems like a fairly common case of tolerance stacking between a tight shell holder and "match" brass. It pays to have a collection of other shell holders in this case.

 

[NorCalMikie]

If you think pressure, I build all my loads with a jam into the lands. I bench shoot so I know what to expect if I pull a loaded round with the bullet stuck in the lands.
A load with the bullet jump to the lands will start showing pressure and a given point.
That exact same load with the bullet jammed into the lands will "not" show pressure at the same point and will allow you to go even higher in powder charge.
Something about the pressure spike? Was explained to me but it's been too long ago to remember the fine points. All I know is it works for me.

 

[LCazador]

Several points here:
- case head expansion is not the subject of this discussion, since it's rarely sufficient to cause interference with the shell holder; there's hundredths of clearance there. We're talking about rim expansion.
- head separation can certainly be caused by overpressure less than required to shear the lugs, although the pressure required will vary by action. The brass simply expands into the joint between the front of the bolt and the rear of the chamber, and ruptures there.

Nothing in the OP's description points to high pressure, rather it seems like a fairly common case of tolerance stacking between a tight shell holder and "match" brass. It pays to have a collection of other shell holders in this case.

The rim is part of the case head. Case head expansion can be measured at the rim or just forward of the extractor slot. The rim, the primer pocket, the extractor slot, and the web compose the case head.

 

[Ledd Slinger]

Brass rims diameters will grow when pushing high pressures but you would have to have a lot of overpressure to make Lapua brass expand bad enough to the point where it wouldn’t even fit in a properly sized shell holder. Primer pockets probably wouldn’t hold a primer anymore at that point. Can always measure a fired case against a virgin case to be sure.

I would suspect the shell holder as others have stated. If a new shell holder doesn’t work, it’s possible that Lapua accidentally messed up that lot of brass. Would be easy to determine if rims have poor concentricity in relation to the base of the case body using a runout tool. Also multiple measurements on the rim with a vernier caliper would tell you if the rims are oblong shape or too large.

I have a magnum size shell holder from RCBS that I have to turn at a 90 deg angle to get it to go in my press ram. Have many RCBS holders including other magnum size and no others do that. Not always perfect machining. It happens every now and then.

 

[Ned Ludd]

I cannot state in your specific case that overpressure is necessarily the cause, but it can happen. I (and quite a few others) have used a fairly warm load for the .223 Rem with 90 VLDs over H4895 in F-TR for years. Primer pocket life of Lapua brass with this load is poor, perhaps four firings at best before the pockets will no longer hold a primer. With brass fired using this load, the issue you are asking about becomes noticeable after the first or second firing. Specifically, the case can no longer be readily turned 360 degrees in the shell holder due to "high spots" at the bottom of the extractor groove. With .223 Rem brass, the the primer pocket depth extends very close to the top of the extractor groove. If the primer pockets are expanding with a warm load to where they eventually won't hold a primer, that means the brass is expanding in exactly the same region as the extractor groove. In other words, the extractor groove represent a region that is relatively unsupported and therefore less resistant to pressure because a substantial amount of metal has been removed in making the extractor groove. By analogy, Lapua Palma .308 Win brass (small rifle primer) can take much higher pressure than standard .308 Win brass (large rifle primer) because there is more metal around the primer pocket to withstand the higher pressure. Likewise, I am fairly certain that of there were such a thing as .223 Rem brass that had no extractor groove at all, it would likely withstand the pressure of this particular load much better and the primer pockets would last a longer than they do. Of course, extracting a fired case might be difficult.

In my hands, this this is unlikely to be the tolerances of the shell holder, as a given shell holder works perfectly on virgin brass, and at least two different shell holders exhibit the exact same issue with a given case not being able to be turned 360 degrees after firing a couple times. Although it is possible that a different manufacturer's shell holder might have a looser tolerance and therefore not exhibit this issue, or that the lip of a shell holder could be opened up a little bit so that the problem went away, I can't imagine that having a "loose" shell holder is a good idea, either. I have played around with the idea of using a ring die (small base die) with the .223 Rem brass to squeeze it down and possibly get a little more life out of the primer pockets by squeezing them down at the very base a little more. I bought one and tried it and I think the idea might have merit, but in order to make it work, I figured out I would have to machine down the the thickness (top edge) of the shell holder so that the ring die could size even further down the case/extractor groove. I haven't tried that as yet.

 

[joshb]

I cannot state in your specific case that overpressure is necessarily the cause, but it can happen. I (and quite a few others) have used a fairly warm load for the .223 Rem with 90 VLDs over H4895 in F-TR for years. Primer pocket life of Lapua brass with this load is poor, perhaps four firings at best before the pockets will no longer hold a primer. With brass fired using this load, the issue you are asking about becomes noticeable after the first or second firing. Specifically, the case can no longer be readily turned 360 degrees in the shell holder due to "high spots" at the bottom of the extractor groove. With .223 Rem brass, the the primer pocket depth extends very close to the top of the extractor groove. If the primer pockets are expanding with a warm load to where they eventually won't hold a primer, that means the brass is expanding in exactly the same region as the extractor groove. In other words, the extractor groove represent a region that is relatively unsupported and therefore less resistant to pressure because a substantial amount of metal has been removed in making the extractor groove. By analogy, Lapua Palma .308 Win brass (small rifle primer) can take much higher pressure than standard .308 Win brass (large rifle primer) because there is more metal around the primer pocket to withstand the higher pressure. Likewise, I am fairly certain that of there were such a thing as .223 Rem brass that had no extractor groove at all, it would likely withstand the pressure of this particular load much better and the primer pockets would last a longer than they do. Of course, extracting a fired case might be difficult.

In my hands, this this is unlikely to be the tolerances of the shell holder, as a given shell holder works perfectly on virgin brass, and at least two different shell holders exhibit the exact same issue with a given case not being able to be turned 360 degrees after firing a couple times. Although it is possible that a different manufacturer's shell holder might have a looser tolerance and therefore not exhibit this issue, or that the lip of a shell holder could be opened up a little bit so that the problem went away, I can't imagine that having a "loose" shell holder is a good idea, either. I have played around with the idea of using a ring die (small base die) with the .223 Rem brass to squeeze it down and possibly get a little more life out of the primer pockets by squeezing them down at the very base a little more. I bought one and tried it and I think the idea might have merit, but in order to make it work, I figured out I would have to machine down the the thickness (top edge) of the shell holder so that the ring die could size even further down the case/extractor groove. I haven't tried that as yet.

I’ve theorized that making a “push thru” type die might work on those. There’s also a guy here that owns a roll sizer. Wonder if he’s tried anything along those lines.

 

[Ned Ludd]

I’ve theorized that making a “push thru” type die might work on those. There’s also a guy here that owns a roll sizer. Wonder if he’s tried anything along those lines.

The primer pocket in a .223 Rem case extends just deep enough that I think the ring die will actually work. It probably will only squeeze down the bottom edge of the primer pocket, but that may be sufficient to get a few more firings out of the brass. I've talked to some people about machining down the top of a shell holder, and there may even be something like that already on the market. I just haven't followed up on it at this point.

 

[Ledd Slinger]

I can't imagine that having a "loose" shell holder is a good idea, either.

A shell holder only needs to fit well enough to reliably exctract a case from the FL die after sizing. Other than that I want as much play as possible around the rim and extraction ring to ensure the brass can perfectly align in the die.
Also a reason why a certain level of play in the press ram is a good thing. Dont want play up and down in the ram linkage, but a slight amount of play side to side can be a good thing.

I also assign specific shell holders to use on dies only and to be used in only one press because the heights of shell holders can vary

 

[Ledd Slinger]

I’ve theorized that making a “push thru” type die might work on those. There’s also a guy here that owns a roll sizer. Wonder if he’s tried anything along those lines.

People have tried to overcome that issue many times over the years. Really no way to reliably tackle it and add significant brass life. The only real way I could see making primer pockets stronger than what Lapua and ADG already have is for a brass manufacturer to implement a steel insert for the primer pocket.

There’s no doubt that ADG and Lapua (perhaps Peterson and Alpha as well) will handle much higher pressure than other common brands before losing a primer pocket so I just load below where I get pressure signs to ensure long brass life. Which is of course still usually higher pressure than what Rem, Norma, Hornady, and Win brass can ever deliver without fast primer pocket failure.

If a person really wants more speed, then the simple answer is to use a larger cartridge or simply improve the case design with a steeper shoulder and perhaps less body taper. The moderate 23 degree shoulder angle of the 223 is a perfect candidate for an improved design if a person wants more speed without having to sacrifice brass life