Help reading primers for pressure

slimjim

chambered221 wrote:

the same principles apply to both pistol and rifle primers. The controlling factor is the thickness of the cup and the amount fire they have.

I don't think you can apply the principles of using primers for pressure signs in pistol cartridges that don't operate with high pressures. The primers don't provide signs appropriate for the application. The .270 Win does.

slimjim

English Mike wrote:

For some good pictures of flattened primers & other issues. go here: stevespages.com/diagno...blems.html

Aloys, this is great! Glad I haven't seen any primers that flat!!!

slimjim

fnuser wrote:

I noticed in your excellent photo's are the marks on the brass that circumference the base this can also be a sign that your maxing out depending on how shiny they are. This is a mark left by raising the bolt on a cartridge that isn't springing back from the initial expansion or pressure spike,

Thanks for the explaination fnuser. I understand the affect that you are describing. I will disgard any cases I may have this occur on in the future if I every get these signs of overpressure which I will avoid to the best of my abilities.

Stovey - notice he like the pictures!!!

Aloysius

Credits to the one who earned it. In this case English Mike showed the way to Stevespages (which is also one of my favorits, together with thedisease.net/?ejacul...%20Manuals when you couldn't find that gunmanual anywhere)

slimjim

Aloysius wrote:

together with thedisease.net/?ejacul...%20Manuals when you couldn't find that gunmanual anywhere)

Wow!! The world's knowledge base just got bigger! That's a great find!! Thanks, Aloys!!

You know, that deserves it own post so its easy to search for and find.

stovepipe

slimjim wrote:

Stovey - notice he like the pictures!!!

That pic of the 9mm on the right is hilairious! Primer? What primer?! Laughing

I also stand by my last post.
I also inspect the snot outta my 300 cases.
Some are on their 3rd loading, have yet to grow and they'll be tossed after #4, regardless. I keep my pressures DOWN, the cases don't grow, I neck size only and inspect for head sep.

I don't see any advantage to super fast, hot hand-loads and all the other issues that come with same.
I'm mostly reloading the 300 for a savings in $ and (maybe) some wear on the gun and parts. And me. Very Happy

If I want to hunt or shoot full power 'nth degree speed, I'll buy a box of factory hunting/match stuff, The Mossy one-holes factory stuff (if I can hold) but the body suffers. My challenge is to match factory accuracy with a reduction in abuse. That aint gonna happen in my case running pressures UP.

YMMV! Very Happy

chambered221

Slim, maybe I don't understand what it is your saying !!!

All I'm trying to say is you can read the primers the same regardless what it's application is. Overload a 45ACP and you'll flatten the primer just as you can with your .270. The primer design itself is what makes it tolerable for a particular application. (cup thickness and strength of metal)
This is why you see the Rem 6 1/2 & the Fed 200 only listed for cartridges like the 22 Hornet and other lower pressure applications. Use those primers in a in a .17 Remington and it will look as if you got problems at moderate loads. Very possible you'll pierce one in the process.

The same will hold true if you use a standard small pistol primer in a .357mag with a good dose of H110 or W296.

I ended up with some 9mm brass once that had some real ugly primers in them. Turns out the guy that shot them was making "major class" with them in USPSA. That's well beyond a safe book load !!!

slimjim

stovepipe wrote:

That pic of the 9mm on the right is hilairious! ... I also inspect the snot outta my 300 cases. Some are on their 3rd loading, have yet to grow and they'll be tossed after #4, regardless. I keep my pressures DOWN, the cases don't grow,

Stovey, fnuser was refering to close-up shots of my .270 primers.

I have found my .270 shots most accurate when the case volume is near full. Basically run at max load on my handloads. I've had a have had a few cases grow in length but load at least 12 times and some more than 16. Why would you throw out your cases after 4 shots? 300 Win Mag pressures are no higher than .270 Win.

slimjim

chambered221 wrote:

Slim, maybe I don't understand what it is your saying !!!

I thought about it a bit more and thought I'd try one more time.

Below is a picture of my Glock primers from .40-cal cases. 9mm look the same. The primers don't even begin to show any flatness. When I check the Hodgdon website for load data, it shows max pressures just above 30,000 PSI, half the pressure of my .270. Why would I expect to see any pressure signs on a primer (unless I'm using the wrong ones like you pointed out) with max pressures so low to begin with? I wouldn't. If there were signs of overpressure on my Glock primers, I'd be so far over it would be of little use. On my .270, the primers start to flatten as I approach max. If I tip-toe over, it get craters on the firing pin dimples and I think I had one case extraction mark like fnuser described.

So what if the Glocks have rectangular firing pins.

stovepipe

Slim- agreed on the full case theory. Your primers look fine, as well.

Yeh- yer right, 4 seems a bit premature. I'll toss them at 5 then. Wink

Inside joke, I might have the wrong reloader. Embarassed

If I get 4 before a ridge starts or I get signs of wear I'll be happy. This brass aint much thicker than other stuff half it size and it's burning a lot of powder. I don't see them lasting all that long. But we'll see. I got plenty.

*

Firing pin drag marks are caused by the barrel tipping down prior to slide seperation. Too hot a load or too soft a spring, generaly.

YMMV! Very Happy

chambered221

Slim, Is it your believe that reading pistol primers for load development offers no useful information ???

stovepipe

As a reloader, I read all my primers!

slimjim

chambered221 wrote:

Slim, Is it your believe that reading pistol primers for load development offers no useful information ???

No, primers can tell many stories or provide indicators. I just wouldn't expect pressure signs in my Glocks.

chambered221

So it's safe to say you wouldn't expect a pistol primer to flatten, crater, or leak some gas ???

stovepipe

In a revolver? Yes.

In a published safe .45 ACP load used in a Glock, no. The pressures are low.

9MM, 40 S&W and 357 SIG? Watch it, yer running high-pressures in those loads. Chambers in auto-loaders are not that robust. You go over the published limit and you need a new gun. Double charge and you need a new face. Primers already look well impacted w/ factory type and +P pressures, in a lot of cases. You can easily destroy a gun before you totally flatten or badly crater a primer in these.

Auto-pistol loads should be worked up VERY carefully, there's a lot going on at once and they are not even half as robust as revolvers.