primers flattening with no other signs of pressure?

rammac

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Try rubbing a little case lube or light oil on the body and firing one. If there is excessive clearance between the case head and bolt face the primer will protrude back into the bolt face before the case slides back once released from the chamber walls as the pressure drops a little. Lubing the case slightly will allow the case to thrust backward to the bolt along with the primer then expand completely to the chamber walls. If excess clearance (from undersized brass ie- shoulder too far back) is the culprit that fired case should show no primer flattening. If that be the case then readjust your sizing die for less shoulder 'bump'.

Why not just turn the resizing die counterclockwise a 1/8th turn or so (reducing the shoulder bump) and see if the primers aren't as flat? That's safer and has less potential for other, more dangerous problems when you lube the case.

Personally, I think you're worried about nothing. As said earlier, the primer is still round, the gap between the primer cup and the case pocket is still there, and there is no cratering, so I'd say that you aren't seeing too high of pressure, just the effect of too much shoulder bump.
 

Plinker147

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I’ve used plenty of Winchester and never had them show false signs of pressure. So I would say something is causing pressure. But primer flattening isn’t the only sign soil your not seeing the other signs of pressure you might be safe. I still would exhaust other ideas before increasing charge weight
 

Bob Wright

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I would bump shoulders .002 and allow up to .003, and see if that helps. I sample the loaded lot for chambering. Varget is good powder in my 30-06, but it pokes along at 2700 in my 24" barrel shooting a Barnes 168.
If that primer is slipping out against the bolt face and cartridge slams back into it, it could be nailing those primers. Thats where I would start, looking at headspace, and primer seating, maybe slower powder and a different primer. Some of my FED primers do not seat as deep as others. Just go back thru everything and see what changes make the problem less severe. Test at the lower powder charge where the primers are flattening a bit using your fire formed brass with .002 bump.
 

Bigeclipse

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I would bump shoulders .002 and allow up to .003, and see if that helps. I sample the loaded lot for chambering. Varget is good powder in my 30-06, but it pokes along at 2700 in my 24" barrel shooting a Barnes 168.
If that primer is slipping out against the bolt face and cartridge slams back into it, it could be nailing those primers. Thats where I would start, looking at headspace, and primer seating, maybe slower powder and a different primer. Some of my FED primers do not seat as deep as others. Just go back thru everything and see what changes make the problem less severe. Test at the lower powder charge where the primers are flattening a bit using your fire formed brass with .002 bump.
I can try that but even the lower range of powder had the same amount of flattening as the upper I tested so either im getting early pressure signs for some reason OR maybe it is just the batch of primers or something else.
 

Rardoin

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Why not just turn the resizing die counterclockwise a 1/8th turn or so (reducing the shoulder bump) and see if the primers aren't as flat? That's safer and has less potential for other, more dangerous problems when you lube the case.

Personally, I think you're worried about nothing. As said earlier, the primer is still round, the gap between the primer cup and the case pocket is still there, and there is no cratering, so I'd say that you aren't seeing too high of pressure, just the effect of too much shoulder bump.
Nothing unsafe or dangerous about having a little lube on the case for diagnostic purposes. I do it on some AI chamberings during fireforming. It is nothing new. It will give you a very good idea of your bolt face to shoulder dimension (at the chosen datum) with a single moderate pressure firing. If the OP would do that test then he would have a baseline as to where to set the die assuming the lubed case is at maximum length for his chamber minus springback. If the OP is sure that this rifle does not have headspace exceeding SAAMI specs it is a reasonable and easy test with much info to glean.
 

Bob Wright

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I can try that but even the lower range of powder had the same amount of flattening as the upper I tested so either im getting early pressure signs for some reason OR maybe it is just the batch of primers or something else.
I agree, except you are bumping too much. It may work, but to chamber properly and extract, .005 is excessive. May not be the only problem, but its not helping you either.
 

Pinoniper

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All the reloading manuals I have read indicate flattened primers is a serious sign of pressure. No other signs needed.

I would try a different projectile.
 

gvjm

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I’ve found that this is common in Semi auto rifles. Magnums too. If your not getting any other signs, I’d go with it.
 

epags

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Oxnard, CA
One change at a time:
1. Reduce the bump and try a couple of rounds.
If flattening is still there, just try a different primer brand OR if you have a different batch number for the Winchester primers try to see if the problem goes away.
 

Bigeclipse

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One change at a time:
1. Reduce the bump and try a couple of rounds.
If flattening is still there, just try a different primer brand OR if you have a different batch number for the Winchester primers try to see if the problem goes away.
I tried changing the bump this morning, primers are still the same flattening as before although I did notice when seating primers they were slightly too easy to seat. Can this have issue? Anyways, i will try some cci primers next
 

epoletna

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Primers that are "too easy to seat" makes it sound like your primer pockets are enlarging. I cull brass that feels like the primer goes in too easily.

That said, I would expect to see serious primer flattening and cratering before you reach pressures where the pockets were being enlarged. Your photos don't make it look like you have those kinds of pressures.

If your primer pockets are indeed becoming larger with firing, you need to reduce loads. How many times has this brass been reloaded?
 

Bigeclipse

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One change at a time:
1. Reduce the bump and try a couple of rounds.
If flattening is still there, just try a different primer brand OR if you have a different batch number for the Winchester primers try to see if the problem goes away.

Primers that are "too easy to seat" makes it sound like your primer pockets are enlarging. I cull brass that feels like the primer goes in too easily.

That said, I would expect to see serious primer flattening and cratering before you reach pressures where the pockets were being enlarged. Your photos don't make it look like you have those kinds of pressures.

If your primer pockets are indeed becoming larger with firing, you need to reduce loads. How many times has this brass been reloaded?
I just loaded a federal primer into the same exact piece of brass that I just annealed, resized and it was much more firm to seat so i don't believe primer pocket issue AND it has much less flattening after being fired. Please see the picture. What does this mean exactly? Can I not use the other primers as those are what I did the load work up with and actually found a very accurate node .3moa.
 

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