Primer back out

[2023Mar]

single shot 32-40 caliber, using 13 grains of 2400, with a 170 cast bullet,
after firing primer protudes from brass approximately 3+- thosandth. stopped after firing 5 cartridge as the results were the same. I suspect it is a head space problem? I am considering rebore chamber, any suggestions for other fixes?

 

[C.E.Smith043]

How did the primer pockets feel when seating the primers?

 

[2023Mar]

Had cleaned primer pockets prior to reloading, slight resistance when loading.

 

[C.E.Smith043]

If they didn't feel good and tight that might be part of the problem.

If you have a different brand primer you might try it and maybe it will fit tighter.
And then see if it still backs out.

I'm not familiar with this cartridge, but don't over-look too light of a powder charge and or too fast of burning powder.

 

[PDS]

That is usually a sign of a low pressure load. There is enough pressure for the case to grip the chamber wall but not enough to push the case head against the breech face. The primer backs out until it hits the breech face.
If the fired cases slide into the shell holder ok you don't have a problem.
Back in the late 60's I had an 8mm Mauser that did this with Remington factory loads ( low pressure) but not with military FMJ loads.

 

[dellet]

That is usually a sign of a low pressure load. There is enough pressure for the case to grip the chamber wall but not enough to push the case head against the breech face. The primer backs out until it hits the breech face.
If the fired cases slide into the shell holder ok you don't have a problem.
Back in the late 60's I had an 8mm Mauser that did this with Remington factory loads ( low pressure) but not with military FMJ loads.

Only thing to add is that it is absolutely normal for a 32-40, 30-30, 38-55, most rimmed rifle cartridges. More so with Blackpowder era cartridges, Ike the 32-40.

Basically you most likely have .003-5” headspace.
You could check it by seating a primer .005-010” proud and softly closing the action. Measure the primer height above the case head, there’s your headspace.

 

[fkimble@charter.net]

Combo of too much headspace and low pressure. The primer can only back out equal to the amount of head space. Too low pressure does not push the case head back to the bolt face to reseat the primer. As mentioned this can be normal on older low pressure calibers. Tighten your head space. May need to back off your sizer so it only neck sizes for a couple reloads. Low pressure is not going to fully expand the case to the chamber for several loadings if at all.

Frank