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take me on directly

dennis, don't get your underwear in a knot.

He's having fun with a fun subject and it isn't at anyone's expense.

Chill dude.

SKIP
USMC 1973-1979
Born Again 1983-Eternity!

The remark wasn’t directed at you and I didn’t ask for your guidance. I’m still waiting for his response at my E-mail address in my Public Profile.

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If you want to take me on directly then my E mail is in the Public Profile. I see yours is not. dennis40x

No, Sir, absolutely not. I have no problem with you and have no desire to take you on.

The “engineer” statement in my previous post was not intended to offend yourself or any other member of engineering profession which I have utmost respect for. However reflecting on your post I came to the conclusion that including it was unnecessary and insensitive on my part and have edited my post to remove it.

My private email is added per your suggestion. I welcome correspondence from any member of this forum who wishes to communicate with me in private. However as a matter of principle I shall refrain from responding to any correspondence which I may deem as disrespectful, offensive or even disturbing to myself or other members.

rozenbem

Gentlemen,

First of all let me apologize for my sudden disappearance. I updated my profile to include email and avatar without realizing that my membership along with freedom of speech would be temporarily suspended until new profile is approved. Anyway I am back now enjoying my rights under First Amendment.

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Skip:
You did read the whole thread! And thanks for keeping in the tradition of the thread, more than likely you will become the "fourth disciple"!

Thank you, Skip, I am really flattered.

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Paul:
It is normally assumed the primer on a revolver unseats the amount of head space present and then is reseated under recoil. While it's unseated, there isn't any external support for the cup, so it can spread somewhat and then the outer most portion doesn't fit back into the primer pocket. That causes it to deform, like what you're seeing (BTW, outstanding pictures!).

Paul, this is exactly the pierce of the puzzle I’ve been missing. Thank you! It seems obvious that internal pressure alone would have created a hernia-like shape with budging and rounded corners inside and outside. What we observe in this picture is sharp internal and external angles. However if one considers unseating and reseating of the primer cup during the burn cycle then pieces fall back in place. As you pointed out, following detonation primer first backs out and the unsupported parts spread out under increasing internal pressure. Under same pressure case then moves back onto partially spread out primer. Walls of the primer pocket act as sitting die pushing excess of budging brass down to the bottom of the cup. This sequence would indeed generate the observed shape. Perfect! This also explains why one doesn’t see this type of deformation in sealed primers cases – primer just doesn’t back out if it’s sealed.

Now, I think everyone agrees that appearance of the primer is indicative of relative pressure. The more pressure the more flattening and spreading one will see. The question is – how to interpret this appearance in terms of caliber pressure limit? Or in other words when one should be alarmed about pressure not just increasing but going into the red zone? Given that different calibers have vastly different pressure limits, I don’t understand how same deformation of the same primer in nearly same case can tell me that I am going overboard in both 38 spl and in 357 magnum load.

Also of note. While developing the H110 load I gradually increased amount of powder starting 18.0 gr. which is BELOW permissible limit for this powder. Based on Hodgdon data, “do not reduce amount of H110 more than by 3%” rule would point to 20.4 gr. as a low limit. I observed spreading flat primers in all loads made between 18.0 and 21.5 gr.

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Paul:
BTW, outstanding pictures!

Yes! This is where I get to claim benefits of experience dating back to pre-digital times. Okay, okay to B&W times. And, no, halt that thought! Back then they already weren’t just using 5x10” glass slides with black hood over head …

Mike

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Skip:
Have you shot them at night? I can only imagine what that would look like!

Skip,

I neglected to respond to this question, sorry.

There is no need for that - the load is blinding under broad daylight... I particularly enjoy firing all 5 in rapid succession from 2" 640 And, yes, endshake is 0.04" and growing, thank you very much for asking.

Practicing at distances of 5 yards or less is not recommended - target is usually blown away by the first shot. When I practice with this round range folks tend to congregate behind my back exchanging explicit remarks which I am sure are directed against dated target support equipment.

One concern I have with this round is that if I ever have to use it for real and bg does not expire on the spot from sensory overload caused by a warning shot, I may be found liable for cruelty to the animal and forced to pay for lifelong treatment of posttraumatic stress disorder.

since we're talking about primers:

This seems to be a good time to discuss guidelines for doing so.

As some of you may recall, I had an "overpressure" incident last June--I shot a cylinderful of 38 Spl-GDSB135JHP reloads that had about 17 to 18 gr. of AA#7 in them. The revolver--a new 640--did not blow up, and was still shootable. (If you're so inclined, you can read the reports on this here: ). I posted pictures of the primers and cases here:

Note that though the pressures generated by these rounds were calculated to probably be something between 55,000 and 72,000, the primers aren't pierced, and arguably, not even with a lot of flow.

Now I'm starting to load SR-4756, and arguably will be working my way towards "the load"--depending on the results I get on the chrono, I will stop with what I like for use with the Speer 158-gr. LSWC-HP bullets. So, I'm looking at gathering all the data I can.

So far, I think I have two a priori assumptions:

1. "Reading Primers" accurately can only be done in analsys from one firearm.

2. "Every firearm" is different, so you really need to start at the bottom up, and record the data. Since the data includes subjective evaluation (as in "flattened," or "cratered"), we need to assign numerical scales to the different amounts of flattening, cratering, flow, etc., etc.

My question is, what would you include in listing the types of data to characterize primer reading: So far, I think, we have

a. cratering
b. flattening
c. flow

What else should be added?

And then, there's the slight problem that my latest 5K carton of WSPs shows new artwork on the boxes, and the cup is a different color...and, I am guessing, a different metal composition.

Jim H.

May as well add perforation. It happens.

I never consciously read primers. While I do look at them, I really don't base any pressure predictions on reading them. If a load gives me a little more difficulty in extraction AND the primers are flattened/cratered/pierced, I usually surmise the load is too much and I need to back off or otherwise suspend using that load.

Reading primers is entirely too unreliable to use as any sort of definitive "test". I let my guns tell me what is too much, regardless of what the loading data says, i.e. >13.5 gr of Blue Dot is too much in my .357 guns with a 125 gr bullet, even though the data says I can go higher.

The new Win primers are the same as before, just without any plating like the old ones had.

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Originally posted by rozenbem:

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Skip:
Have you shot them at night? I can only imagine what that would look like!

Skip,

I neglected to respond to this question, sorry.

There is no need for that - the load is blinding under broad daylight... I particularly enjoy firing all 5 in rapid succession from 2" 640 And, yes, endshake is 0.04" and growing, thank you very much for asking.

Practicing at distances of 5 yards or less is not recommended - target is usually blown away by the first shot. When I practice with this round range folks tend to congregate behind my back exchanging explicit remarks which I am sure are directed against dated target support equipment.

One concern I have with this round is that if I ever have to use it for real and bg does not expire on the spot from sensory overload caused by a warning shot, I may be found liable for cruelty to the animal and forced to pay for lifelong treatment of posttraumatic stress disorder.

Mike, You fit in real well around here! Just a twinge of fire beneath all of professionalism. I like that. Sensitive yet forceful. I wonder, is there an underlying reason for that? Not to take the thread off topic or anything! HAHA!


As for your theatrics at the range with your load. I did something very similar when I owned a 629 Mountain Gun. I loaded up some flame throwers and went to the indoor range. I'll tell you I was the focus of almost everyone's attention. Then, just like dad used to tell us, (there is always someone bigger) a guy walked in with a 50AE Desert Eagle! Not that dude made some noise! I could "feel" the concussion after he shot that thing!


Oh, by the way, remember your welding safety glasses when shooting your H110 loads!


We need to get a badge made up or something for those that have entered into this area of development!

Mike, I appreciate your comments.

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The remark wasn’t directed at you and I didn’t ask for your guidance. I’m still waiting for his response at my E-mail address in my Public Profile.

I stand corrected denny. Sorry for overstating the obvious.

Paul and Mike,
I'm trying to understand then. Here is a summation as to the reliability of reading primers. It may be that flattened ones aren't the problem we have been lead to believe they are. If the case sticks during the burning cycle then the primer may not be flattened, it may be estruded instead.

I'm not sure I understand all I know or if I am able to put it into words so others can understand it but is that basically what you fellows are saying? Help me here.

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Mike, You fit in real well around here! Just a twinge of fire beneath all of professionalism. I like that. Sensitive yet forceful. I wonder, is there an underlying reason for that? Not to take the thread off topic or anything! HAHA!

Sure. I'll confess my hidden agenda if you promise not to tell anyone. This thread is about to hit it's 5000th visit mark. Quite a milestone! It's a testament to your good self and other founders who made it as popular as it is!

Forgive me for being enterprising here, but the opportunities abound... Perhaps it's time to start running ads on this thread, endorse ammo and reloading products, etc. We could use the proceeds to buy some equipment for pressure testing...

Skip,

Sticky extraction is an indication the brass has been subjected to more pressure than it has the ability to rebound (spring back) from. It's sort of like bending an object further than it needs, so it will end up in the right place, except here it isn't desirable. Normally, cartridge brass will "stretch" with pressure and rebound to allow easy extraction, unless its overstressed.

I believe I saw a post by Ken Ohler where he was going to see what kind of pressures could be seen in primers and the pressures were so high, he scrapped the idea of an article on it.

Sometimes the physical conditions involved in firing a cartridge will give erroneous primer reading results. I shot some .357 Mag loads in a Handi rifle that were acceptable the previous times I tried the load, but found that suddenly it was no longer acceptable. I was using the same receiver this .22 Hornet brass was fired in with a CCI 400 primer (small rifle primer). The 3 cases to the left are easy to see the firing pin indention is smaller than the 5 cases to the right.



That receiver was a shotgun receiver that has a larger firing pin, with a larger firing pin hole and it just didn't support the primer like it should have. When I changed back to the proper receiver, the primer problem went away.

Paul,
I understand that part of the puzzle. What I was thinking about was IF the pressure did reach the level you describe, i.e. the point of no return, (pun intended) is it possible for the case to never return to flatten the primer? In JFH's pictures of his overloads, the primer is not flattened at all. In fact the primer seems to have the same round corners it came with. What is noticeable is the extrusion around the firing pin. That would seem like the logical reaction if the what you have previousley stated was true.

One thing I know for sure, I'm mighty glad JFH's firearm wasn't in my hands when that went off!

Mike, I noticed you are a relatively new member. In fact your start date is about the time I made some phone calls to area code 913! Any correlation?

Skip,

Unfortunately, I don't have any useful insights into ways of reading the primers. My gut feeling is to follow Paul's summation (which is always a good idea since he has much more experience) and use primers as just one of the indications of approaching KB, but not treat them as if they were pressure cups. I know it's not very instructive, but... As far as cratering is concerned, it's not a gospel either. When I fire my G19 which has large square firing pin hole, the hole is firmly engraved on each and every primer - exactly like in Paul's last picture. Some of the loads won't even make minor...

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Mike, I noticed you are a relatively new member. In fact your start date is about the time I made some phone calls to area code 913! Any correlation?

Negative. Really. I don't think they make enough money on private sales to justify a scheme like that.

Mike

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I believe I saw a post by Ken Ohler where he was going to see what kind of pressures could be seen in primers and the pressures were so high, he scrapped the idea of an article on it.

I didn't state this very well. He experienced very high pressures, before any indication was seen on the primers, was what I was trying to say.

I think there would be a head separation before the primer would be left partially unseated. That's probably what you see in Jim's (jfh) pictures of his 640. the firing pin not only ignites the primer, but also drives the case forward in the chamber. If the pressure reaches catastrophic levels, the case is "welded" to the cylinder and the head separates from more head space than the brass can stand.