Flattened Primers/Coining Headstamp Reading

[charliemopic]

I don't have alot of reloading experience nor do I have a chrono.
I loaded some .223 Rem. rounds useing 75gr. bullets pushed with 22gr. VihtaVuori n135 powder and fired them from a Wylde chambered AR. The CCI 400 primers were flattened just a little too much so I assume the charge was too hot. There was no coining on the headstamp.
I also so fired some 5.56 Guatamalan milsurp that did not flatten the primers very much at all but I could clearly see coining of the headstamp, I mean there where clear imprints of the extractor and ejector areas on the headstamp.
I'm not understanding why my handload would get a really flattened primer and no coining and why the Guat would get obvious HS coining and no flattening of the primer?
Any ideas?

Thanks Much

 

[Z-Michigan]

My (admittedly very limited) reloading experience has been that primers often flatten more on reloads than on factory ammo, even when the loads are quite light per load books. I recently loaded some .223 using Remington primers with help from a very experienced reloader, at a fairly mild load per the Sierra book, and the primers were fairly flat but there were no other pressure signs and the rifle functioned quite normally.

Any chance you could take a close-up photo and post it?

 

[Idano]

I have used a lot of CCI 400 primers and they do flatten out pretty good with normal loads. I checked the Vihtavuori web site and if your are using 22 grains of N-135 with a 75 grain bullet and your col is 2.260" your loads should be fine. The load data showed 20.7 grains to 23.3 grains. I know burn the rate shouldn't be an issue because N-135 falls between TAC and Varget

 

[rcmodel]

I'm not understanding why my handload would get a really flattened primer and no coining and why the Guat would get obvious HS coining and no flattening of the primer?

Perhaps the Guatemalan milsurp has harder mil-spec primers, as would normally be expected.

And perhaps the Guatemalan milsurp brass is softer then the brass you used in the first load. Also not uncommon.

Trying to compare handloads in one brand of brass with factory or mil-sup of another brand is comparing Apples to Oranges.

They look completely different, because they are completely different.

rcmodel

 

[ClarkEMyers]

No reason to think it applies here but some primer pockets end up O/S

No reason to think it applies here but some primer pockets end up O/S when the military crimp is removed and so the primer flattens out to the new edge.

As noted it takes more experience than I have to usefully compare apples and oranges - I have enough trouble with same brass reused.

As everybody knows a Chronograph is really useful for estimating pressure differences in controlled conditions but again not so much as between completely different combinations.

 

[Ridgerunner665]

Any "True" mil-surp ammo will have harder primers (CCI 41)

 

[USSR]

Primers will "lie". Extractor marks on the cartridge base don't.

Don

 

[Eagle103]

I've only been reloading for a couple of years and I know the feeling of not being sure about what signs to look for in an overpressure load. The only things I trust are chronograph readings and primer pockets that loosen up by 3 or 4 firings.

 

[snuffy]

Reading pressure signs from primers is like reading tea leaves, or the creases in your palm. Your handloads may have been too short,(excess headspace), allowing the primer to back out, then be nailed back against the boltface when the shell stretched. False reading of high pressure.

 

[stubbicatt]

I like the micrometer method of gaging case head expansion as a method of determining load pressures.

Ejector markings are only helpful with a "button" style ejector such as found on the AR series and Remingtons etc. If you use a fixed ejector style rifle, especially one with an adjustable gas system, your ejector markings are likely to be quite a bit more pronounced and cease to lose their utility as a means of measuring pressures.