Pressure signs?

[Astroangler]

This question is for guys with experience in reading pressure signs. Would you take a look at this picture and tell me if you see signs of too much pressure? Thanks in advance

[/IMG]

 

[rcmodel]

No, I see signs of almost no pressure.

And a gun with an oversize firing pin hole in the slide.

What do factory ammo primers look like?

rc

 

[Astroangler]

I couldn't tell you because all I have left are reloads. However, all of my reloads look the same primer wise. Using Unique and 700x. I was concerned about the 700X in the picture and just wanted to be confident that the primers weren't showing signs of too much pressure. The gun didn't kick like it was using heavy loads, but being that everyone says to "watch for pressure signs" I thought I'd ask, thanks for your input on it.

 

[rcmodel]

everyone says to "watch for pressure signs"

I know everyone says it.

But they don't know why they are saying it!

With almost all semi-auto pistol rounds, your first sign of an over-pressure load will be bulged or blown cases and gun damage.

With centerfire rifle calibers, case head expansion and loose primers is one pressure sign.
Ejector marks on the case head is another where the case tries to flow into a plunger ejector hole in the bolt face.

But that happens at 70,000 PSI or more.

Or about twice the max safe pressure of 35,000 PSI for a .40 S&W.

rc

 

[Astroangler]

Okay, that makes me feel good about what I'm seeing. I have no issues with the brass and I have looked them over for even the slightest crack or sign of cracking and expansion. I'm trying to stay well below the maximum, but using plated flat points-there isn't much data out there for them. I have the new Lyman manual coming to me tomorrow. Hopefully I will have good load data for lead that I can use further in order to find a better performing recipe. Thanks RC

 

[Potatohead]

RC,
You're the man... I read most of these reloading threads (I know, I'm a glutton for punishment) and you seem to be a pretty knowledgeable dude. A "fountain of wisdom"... Thanks for helping us new folks especially...

 

[wackemanstackem]

When you start to see the primers flat against the side walls of your cases you can start to be careful, I see none of that ,look close and you can still see lots of round edges where your primers seat in your cases thats a good thing.

 

[steve4102]

Reading primers is akin to reading tea leaves.

I borrowed this from another forum and I like it.

Think about this: Primers don't know what cartridge they're in.
A small pistol primer in 380auto and a small pistol primer in 38 Super.
The primer is too ignorant to know that it must flatten at 18000psi in the 380
but wait until 36000psi if loaded in a 38 Super. It just isn't smart enough.
Take that Winchester LP primer, good for both standard and magnum cartridges.
How does it know you seated it in a 45acp, or maybe a 44 Magnum?

 

[Nordeste]

I got exactly the same thing with the brass I collected from my Beretta 92FS. I had run Fiocchi, Magtech, Remington UMC and Santa Bárbara ammo through it and in every case the primers were exactly like yours. The Fiocchi and Santa Bárbara ammo were pretty hot. The Magtech and Remington UMC were average.

I suspected over pressure as you did and posted pics here. I got the same reply RCmodel has given you and it makes sense. The Fiocchi and Santa Bárbara are NATO spec ammo and on the hot side, but the Magtech and Remington are not. You could expect to see over pressure signs on the former but not on the latter. It's more likely that it has to do with an oversized firing pin hole and a solid firing pin strike.

 

[wackemanstackem]

Even if the primers are not smart a flattened primer is still a sign of pressure issues.

 

[ljnowell]

Even if the primers are not smart a flattened primer is still a sign of pressure issues.

You missed the point. By the time you see pressure signs on primers in most pistol calibers you are way overpressure, not just a little. Hence its not a good way of looking for overpressure.

 

[wackemanstackem]

Point taken I understand pressure very well and dont have problems with it .I was making a statement to him ,simply and that is a flattened primer is a sure sign of pressure issues.,so if you see flattened primers its never to late to make changes.Maybe they didnt pick up on other warning signs thats all.

 

[gamestalker]

I've split cases a few times with over pressure 9mm loads, and the primers looked no different than those which were not over the top. And in all honesty, this was back when I had first started reloading and was lead to believe that my primers would give me a heads up, wrong. You simply can't gauge pressure for an AL by looking at the primers. And for that matter, primers still don't make for a good method of reading pressures for bolt guns and the like, brass yes. But bottom line is, and providing one is doing everything else correctly, rely on published data, and a chrony, and you'll likely never get in trouble.

GS

 

[steve4102]

wackemanstackem

Point taken I understand pressure very well and dont have problems with it .I was making a statement to him ,simply and that is a flattened primer is a sure sign of pressure issues.,so if you see flattened primers its never to late to make changes.Maybe they didnt pick up on other warning signs thats all.

Flattened primers is not always a sure sign of high pressure, there are other causes as well.

My point is that reading primers is not always a good indication of pressure. To many handloaders are of the belief that primers can tell them when they are over pressure for their specific cartridge. They are somehow of the belief that if the primer is not flat then they are Good-to-Go and still within the "safety Zone". Not so.

Lets compare the 45 ACP (small primer) to the 357 SIG. The 45 has a MAP of 21K while the 357 SIG has 40K. Both take the same SP primer. The SIG will not show flattened primers all the way up to and including 40K psi. Knowing that the SP primer can handle 40K without flattening at what psi would you expect a 45 ACP primer to show signs of pressure, 22K-23K or will that 45 primer show no signs of pressure all the way up to 40K? As stated above, the primer doesn't know what case you seated it in.

A question, at what psi do primers start to flatten and show signs of "over" pressure? I have read that LR primers and other signs of pressure do not rear their ugly head until over 65K and into the 70-75K range, but I have never seen any real test results.
Is there any such study or testing that shows at what PSI primers start to fail and show pressure signs?

 

[gamestalker]

And there are a number of other elements that the brass and primer are exposed to during ignition, and as well, throughout the entire range of the pressure curve that could very well mimic over pressure primer signs.

Also fairly recently I shot some 7mm RM loads my son picked up at a yard sale I think. They turned out to be significantly under charged. And if I were to have used those primers as my only means of evaluating pressures, I would have thought those loads were over pressure, when in fact they were operating dangerously low.

GS

 

[ljnowell]

Another thing to mention is that depending on primer, gun, and load, some primers will be flattened at can be and still be within spec. I have shot 357 ammo that would completely flatten a primer while the cases would just fall from the cylinder when fired, no sticky extraction at all. This was with factory ammo, I am sure it was not overpressure.

 

[gamestalker]

At the end of the day, about the only reliable means of estimating pressures in AL actions is to rely on publish data and chronograph results.

GS

 

[steve4102]

At the end of the day, about the only reliable means of estimating pressures in AL actions is to rely on publish data and chronograph results.

And with that we, Say Good Night Gracie.

 

[wackemanstackem]

I am not arguing any of the points that there are other means when of looking for pressure.I load 40s alot and they are one of the problem childs for pressure,What I am saying and I hope the young reloaders listen is yes you can have a flat primer and it might not be a problem.But 9 times outa 10 if you start to see flat primers and you dont have a chrono and you dont have bulged brass you probably have a problem and its never to late to address it.I look at all my 40 primers when sizing its a VERY RELIABLE MEANS OFF KEEPING A EYE ON THINGS.So to all young new reloaders trust me ,specially in 40s watch your priimers it works!

 

[ranger335v]

"Even if the primers are not smart a flattened primer is still a sign of pressure issues. "

Studing primers as a sign of over pressure is on par with studingthe entrails of a chicken. THE most common cause of primer flatening is excessive headspace. I've seen photos of disintergrated firearms, rifle and hand guns, where the recovered case heads and primers looked quit normal. Flattened primers meant something when they had domed tops, not since they started making 'em with flat tops.

 

[ljnowell]

I am not arguing any of the points that there are other means when of looking for pressure.I load 40s alot and they are one of the problem childs for pressure,What I am saying and I hope the young reloaders listen is yes you can have a flat primer and it might not be a problem.But 9 times outa 10 if you start to see flat primers and you dont have a chrono and you dont have bulged brass you probably have a problem and its never to late to address it.I look at all my 40 primers when sizing its a VERY RELIABLE MEANS OFF KEEPING A EYE ON THINGS.So to all young new reloaders trust me ,specially in 40s watch your priimers it works!

No, it doesnt. They could be flat and in spec, or they could be running 60kpsi and not be flat. It doesnt really work at all.

 

[The Bushmaster]

Primers are NOT a way to check for over pressure. As far as "flattened" primers are concerned, my Ruger Blackhawk .357 magnum always flattens the primers. And I mean FLAT. And I'm not over loading the case.

 

[R.W.Dale]

Primer appearance is wholly unreliable as a pressure indication sort of being pierced or flowing back into the firing pin hole.

I have a scandium 386xl smith in 357 that will flatten small RIFLE primers to the point you can't see the edge of the primer pocket WITH START LOADS sooting up the cases. But it doesn't do this because of an over pressure condition. It does this because the firing pin/breach bushing has a very pronounced convex shape.

Then can take a 9mm NATO case and a SP primer. Seat a 147g xtp long. Load it using 9x23mm data and get nearly 1600fps from a 16" encore barrel. Guess how these primers looked? They looked like they were shot in a 38spl cowboy load

Primer appearance has more to do with what you're shooting a load out of than the load itself

 

[wackemanstackem]

The only primers I flatttend where on my 40s where I pussed loads for testing.Have never flattened any with book loads talking about 20-30 k rounds ,only test loads past book.And did that to see what happens out of my gun.I believe the orig post shows 40s not rifles or any other cal.Goodluck!

 

[RandyP]

I also load plated bullets like the OP for four calibers and simply keep my charges at the higher end of bare lead/mid point of FMJ using Win 231/HP-38.

Berry has specs on their website for max FPS but I don't own a chronograph or have an LGS indoor range that would let me set one up.