Deep Pockets?

[Coal Creek Griff]

No, I'm not talking about rich folks.  I'm talking about primer pockets.

I've done some loading for my Uberti '76 carbine in .45-75 and I've had a couple of failures to fire.  In each case, the second or third hammer strike would fire the round.  The primer seemed to be fairly deeply indented, but I also noticed that the primers seemed to be seated further below flush than I'm used to.  I wondered if my brass, or some of them, have deep primer pockets.  The mainspring is stock and seems to be heavy enough.  In the future, I'll segregate the ones that don't fire and try to do a comparison, but I wondered if anyone else had experienced anything like that.  The brass is Jamison .45-75 brass and the primers are standard Winchester LR.

Any similar experiences or other thoughts?

CC Griff

[King Medallion]

I have not had any issues whatsoever with my 45-75 Jamison brass.

[Cliff Fendley]

Oddly I'm actually having the same problem with mine. I have a few fail to fire and some of those do fire after a couple tries but I have some rounds that still refuse to fire. The primers look dented pretty good. I first thought I had a bad box of primers but I haven't had any failures in other calibers using the same primers. They are Federal rifle primers. The main spring seems stiff enough.

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[King Medallion]

My primers are regular WLR.

[Coal Creek Griff]

Posted by: Cliff Fendley
Oddly I'm actually having the same problem with mine.

That's interesting.  I'll have to try to measure the pocket depth for some of this Jamison brass (I'm assuming that you're using Jamison as well).  I've never tried to measure pocket depth before.  It will be interesting to see how accurately I can measure it.

CC Griff

[Cliff Fendley]

yes is is Jamison brass. The primers are slightly below flush but they don't seem particularly bad. but something is the problem. I wish I had a different gun to try but only own the one 45-75.

[Coal Creek Griff]

I used my calipers to measure a handful of unfired brass.  The pockets were all at about .131-.132.  I also measured the pockets on a handful of unfired Winchester .45-70 brass (it's what I had nearby at the time).  They gave similar measurements, but this was only at the flash hole; there may be more variance at the sides of the pockets.

I don't know what the problem is here.  I'd ordinarily look at the main spring, but it definitely seems strong enough.  An issue with the firing pin or the return spring is a possibility, but the primers seem to be indented enough.  My thought had been that the primers were not fully seated, absorbing some of the blow.  They were seated below flush, but if the primer pockets were particularly deep, they might not have been fully supported.

Again, I'll probably sort out the ones that fail to fire and measure those pockets to see if they are different.  Maybe we both had some bad primers...

CC Griff

[Cliff Fendley]

I haven't measured any of mine but that's about right but getting to the max depth. 125 to 132 is spec for large rifle primer pocket. I uniform the pockets to 128 if they will clean up at that but I've only done that on my modern long range cartridges like 308 and 7mm. Never done it on my black powder cartridges.

[matt45]

Not an expert, but- when I first got my Uberti (45-60) I had a few failures to fire.  I uniformed my pockets and increased the hammer tension a little.  I haven't had the problems since.

[Sloan Dodgy]

Another thing to check is case (not cartridge) length and/or crimp.  I've run into weird problems with a couple other rifles or revolvers that ended up being either cartridge cases being ever-so-slightly too long for their particular chambers, or very slightly bulged at the crimp.  The cartridges would chamber seemingly OK, but the effective over length interference at the end of the chamber would result in the first hammer fall being cushioned by driving the cartridge home just a smidgeon. They would usually fire on the second or third try.  Drove me crazy until I figured it out and trimmed the cases just a bit short of spec to fit those particular chambers.

[Cliff Fendley]

No on mine it's happening on first firing of new brass which just falls into my chamber. This brass is undersized new, at least for the chamber of my gun.

[Coal Creek Griff]

My instances happened with previously loaded brass, but they were full-length resized and they easily fall into and out of the chamber.

On another note, I didn't have any such issues last weekend, firing about 25 rounds without issue.  On the other hand, the specific pieces of brass that had previously caused me problems were not among those 25 rounds.  When repriming the cases, I noticed that some primers seemed tight in the pockets and I wondered if I had simply failed to seat them deeply enough (I always assume that I'm the cause of any problems I encounter).

We'll see how the next shooting session goes.

CC Griff

[Dusty Boddams]

CCG, have you checked to make sure there is not a head space issue on the rifle or something bent at the links in the action? Because the primers set at under flush shouldn't be an issue. Just a thought.  Dusty Boddams