quote:

Originally posted by Erich:
I suspect he meant that the reduced SAAMI .38 Spl pressure standards were implemented during that time period, not that at that time SAAMI sprang Athena-like into existence from the head of the federal Zeus.

This thought was interesting, but I don't get your meaning:

quote:

the wimpification of loads is due in large part to a better understanding of QC statistics in more recent times.

Would you explain this further please? Whose understanding of quality control having to do with what?

Thanks!

OK, Erich, I will try to expand a bit on the above. From one perspective, it has to do with a better understanding of how things fail. From a second perspective, it has to do with a better understand of performance disctribution of the prodict and it components. You have probably heard of the ISO 9000 series of standards that US companies are courting and have been for the last two decades. You may have also heard of the Six Sigma concept. The basic idea behind all of these is that as a manufacturer you have the procedures in place to not manufacture faulty parts from the beginning, and to detect any before they are incorporated into your product. That way every piece that goes out the door meets all specs.

From an ammo manufacturers point of view, this means that every primer pops when struck, when the powder burns you get the "same" velocity, and every bullet exhibits the same terminal performance. It also means that you produce the "same" pressures and that they fall within spec. You may remember that soem years back people were referring to the Maximum Product Average pressure. That name is gone, because it wasn't rigorous enough. The values stayed the same, but they are now referred to as the Maximum Probable Sample Mean. SAAMI also lists another pressure as the Max Probable Lot Mean, which is lower than the MPSM, and an additional value called the Maximum Average Pressure, which is below the MPLM. The relationship between the latter two values is that the MAP is positioned such that you have a 97.5% probabllity of any lot not exceeding the Max Probable Lot Mean. And the Max Probable Sample Mean is set 3 standard errors above the MPLM: no single sample of ten rounds will be found above the MPSM.

For the sake of numbers, I'll use the still current CUP standrd for the .357. For the .357, you may have seen a value of 46.5 KCUP. That is the MPLM. If you had loaded a 1000 round lot with the 46.5 KCUP as its mean, you have a grossly overpressure load. By definition, you would have 100 10-round sample of which half (50) would have been below the MPLM and the other half (50) would have been above the MPLM. And you can be pretty certain that at least one would have exceeded the Max Prob Sample Mean.

What would be your response? Bring the working pressure way down. Now complicate the picture even further. The pressure values in the SAAMI standards are bsaed on the stats compiled by the ammo manufaturers who make millions of rounds in any loading and test 10s of thousands of them. They know how reproducible their pressures are. The SAAMI specs rely on that. Now you are a makr of reloading components and you want to put out a reloading manual on how to use your products properly. What is the variability on your customers' reloading techniques? Is it as low as those of the big manufacturers? How do you incorporate the increased variability that you expect to see in reloaded ammo? Look at Lyman's manuals, which still use the CUP standard for the .357. The only load to 42K, not the 45K that is the current MAP for the .357. That 3K difference amounts to about triple what SAAMI expects from the big boys.

Now let's talk briefly about how things fail. There has been a lot of talk from folks taking part in this little exchange that their guns haven't blown up, so the load must be safe. There has also been more than one comment that they haven't heard any reports on guns failing. My reaction was that you guys just plain don't get around enough. In 1972, Bill Caldwell, then the chief ballistics tech at Speer, published an article in Handloader Magazine on the interesting things he learned after he got the new piezoelectric pressure system. He even went so far as to have Speer makea special single-shot cylinder for two revolvers, IIRC, that would accept the pressure transducer.

One of the motivating factors that he mentioned was the problem they saw with bent cranes on Model 19s. He reported on a study he undertook to see where the revolvers streched dynamically when a cartridge discharged. Now you also have to understand something about Caldwell's results. They were measured with the transducer over the case mouth, not over the cartridge. SAAMI's current standard requires measuring the pressure over the case with the transducer located near the base of the bullet. And that statement shoud make any thinking individual ask the question on how they handle the issue of short seated lightweight bullets and deep seated heavyweights? Do they have a different barrel for each load? Caldwell's measurement were made using what is currently the CIP method. So you can see that even once the new pressure measuring systems came on line, they may not have been used consistently from one lab to the next, and Speer's data will have changed over the years because of how they measured the pressures.

From an engineer's perspective, the statement that an individual gun had not failed catastrophically proved that a load is safe, is sophomoric. And I mean that literally, you would only hear that from someone that hadn't gotten past his sophomoric year in college. Firearms fail from a whole spectrum of methods. Ideally, as a designer, you would like a firearm to fail from one of the high count mechanisms like chamber throat wear or forcing cone wear/cracking or going out of time or increased headspece from standard pressure loads. You don't want it to be from a low count mechanism like forcing cone wear from highly erosive loads or stretched frames or bent cranes or bulged bolt cuts from excessive loads.

Firearms are basically designed with a factor of safety of 2 or greater, based on the max operating pressures. Anyone can push the pressures over the max operating pressure for the cartridge and reduce the safety factor, but now you have to ask at what round count does the failure occur and does it change type.

If you were old enough to have read Skeeter Skelton's articles, you might remember him having to tell his readers about a favorite load that he recommened for use in the 1917 Smiths that he liked so much. In the particular instance that I am referring to, one of his compadres reported cracking a cylinder on his 1917 with Skeeter's load. Skelton told his audience that while his gun did not seem to mind the load, he was recommending reducing it by one-half a grain. My point here is that saying an individual gun did not have trouble with a given overload, it does not nmean that other examples of the same firearm won't. And don't forget that total round count is a major factor here. You've only fired 100 rounds and report that it is a great load, I've fired 1000 and my gun is now having problems. That is one of the issues here. Not only individual differences in the firearms themselves but the number of times a gun has been fired with a given (over)load.

This message has been edited. Last edited by: Mack Heath,

Very interesting read - thank you for taking the time to write it up! Wow.

quote:

Originally posted by smith crazy:
I did do a little research after posting this morning and found something ironic.

In the #47 and #48 Lyman manual there is a load listed with SR4756 and a 110gr. JHP. What I found amazes me. They list a load of 7.7gr for a +P load with a CUP pressure in the 17,000s. Now common sense should tell you that the pressure isn't going to be double + by going to a 158gr. bullet. Not to mention the fact that it is lead that Eric is using and therefore pressure isn't going to go up relationally. Lead = less resistance than jacketed = less pressure.
Just thought I would throw this in as I endeavor on my fact finding mission!

WRONG, WRONG, WRONG. there are two fallacious statements made above.

First, by going to a 158 from a 110, you are changing TWO critical parameters: weight and seating depth. I don't use 110s so I cannot tell you how long a 110 is, but I do hve 125s and 158s. A 125 Speer GD is 0.529, while the 158 Speer GD is 0.639. That 0.110 inch difference tranlates DIRECTLY into a 0.110" difference in seating depth. The length differnce will be even greater for the 110.

Now let me give you some real pressure values, yes measured with a real pressure gun, for the effect of just increasing seating depth while using the exact same bullet. These data were measured by the Hercules ballistics lab for the NRA.

The cartridge was the .38 Special, the bullet was a 148gr wadcutter. Two charges were tested: the standard target load of 2.7 gr of Bullseye, and a double charge of 5.4 gr.

In the first test two seating depths were examined: flush and deepseated 1/8th inch below flush. For the fluch seated bullet the pressures were 8.7K PSI, for the deepseated bullet the pressures were 16.1K PSI. Not quite double, but pretty darned close (185%).

In the second series, they looked at the same two seating depths, but used twice as much powder. For the flush seated bullet, the pressures were 32.3K PSI and for the deepseated bullet, the pressures were 55.5K PSI. In this case, the difference was a 70% increase due to just the deep seating

Now take into account that you are adding 40% more bullet mass to push and it calls into question how far "common sense" can take you in the world of internal ballistics.

Also, don't read too much into the difference between lead and jacketed bullets. Lead has lower friction, but being softer than a jacketed bullet can slug up more when it hits the forcing cone. It is very difficult to predict where the pressure will go with a revolver.

quote:

Originally posted by 38-44HD45:
Well, I don't know when SAAMI arose, and I have no reason to believe that you are incorrect about the 1926 date. I'll take you at your word, Mack. But I do know that the reliance of commercial ammunition manufacturers on SAAMI recommendations did not become widespread until much more recently. Exact date? Can't tell you. My "provenance" is from having spent lots of time in '94, '95 and '96, working with folks from a major ammo manufacturer, with some guys who had been inside the business (unlike SAAMI, then or now)

I want address one more thing and then get out of here. The very last statement in the quote above represents a very common (mis)perception in the reloading world and represents a profound misunderstanding. SAAMI IS the industry. SAAMI specs are made up the same way that the ASTM (American Society for Testing and Materials) makes up its specifications. The technical committees are made up of members of the industry and interested outsiders.

SAAMI is NOT an outside organization that orders the industry around through its specifications and standards. Go over to the SAAMI website and look to se who the members are. Those are the organizations that are contributing to the standards.

Also, you need to understand that the SAAMI specs are voluntary. Nobody HAS to follow them. They exist so Manufacturer A can build a firearm that will chamber and safely discharge a cartridge made by Manufacturer B.

If an ammo maker wants to market a +P+P+P+P+ round, there is nothing to stop them.

quote:

WRONG, WRONG, WRONG. there are two fallacious statements made above.

First, by going to a 158 from a 110, you are changing TWO critical parameters: weight and seating depth. I don't use 110s so I cannot tell you how long a 110 is, but I do have 125s and 158s. A 125 Speer GD is 0.529, while the 158 Speer GD is 0.639. That 0.110 inch difference translates DIRECTLY into a 0.110" difference in seating depth. The length difference will be even greater.

Thank you for your response, obviously well educated in this area. I went back and checked what OAL was for the different bullets and found only .050" difference there. Now again I would have to state it would seem to me that double the pressure would be a bit much. An increase? Most assuredly, double, not likely. There are some powders that have a pressure curve like that without a doubt. It doesn't look from other data that SR4756 does. I could be wrong on that aspect and will do some research come Monday.

Thank you for your comments again.

I understand the affect of having more projectile in the case on pressure. In fact, that is why Elmer Keith made his bullets like he did. Same weight bullet, even heavier, with less of it in the case.

Erich:

I enjoy your posts a lot. We seem to think alike in many ways. Your "back to basics" experiment is a terrific idea and I am looking forward to your final report on that topic.

But with all due respect, I'm quite puzzled by your experiments with SR4756.

You obviously have a very pragmatic and sensible turn of mind. That's what leads you to experiment with basic, plain vanilla .38 Spl. revolvers. That's why your tag line stresses that good shot placement and adequate penetration are the true variables to stopping power--the rest is voodoo and magic.

So here's what I don't understand. You can get 1000 fps from a .38 Special using perfectly conventional loads and good ol' Unique powder. So why fool around with controversial loads of SR4756, which only gain you 200 fps? What practical benefit do you obtain from that extra 200 fps?

One of the reasons I like .38 Special so much is that I prefer the K-frames to the N-frames, and my "control threshold" in the K-frame seems to be a 158 grain bullet at no more than 1000 fps. Since I can get that with a perfectly safe, entirely conventional .38 Special load, I just don't see much need for a .357 in that frame size. I spend most of my time shooting a Model 19, so it's not an issue of whether the gun can take the increased pressure, it's that I don't see much marginal return in shooting something beyond a hot .38 Special.

Furthermore, if I really needed more horsepower, I'd go for a .44 N-frame (or a rifle), rather than adding 200 fps to a .38 bullet.

So inquiring minds want to know--what is it about the prospect of obtaining another 200 fps from a .38 slug that motivates such a pragmatic fellow to search for that performance?

Swede,

I'd be happy to continue to talk about the load at proguns, but I won't do it here. You are welcome to read my rather detailed posts on the load in this section of this forum.

I'm late to this party but have got to display my crass ignorance too.

I've enjoyed experimenting with propellant powders in handloading experiments over the years and the .38 Special is one of my favorite rounds to play with. Sure, there's been some really hot loads published in various sources over many years. I can think of a certain book in my library that recommends a .357 Magnum load with charge of 2400 that would be compressed if one tried to load it.

There's a jillion safe, sane loads for the .38 Special that will answer any need that requires the application of .38 Special performance. It can be instructive though to try something different or tweak for performance.

There's lot's of .38 Special revolvers around here but I primarily handload for three revolvers in particular. These same revolvers have been used for every .38 Special concoction I've made in the past 30-something years, from mild to wild. There has to be something said for long familiarity with a gun and how it responds to various loads. It's not scientific but it is observable and illuminating. If one wants to "push the envelope" the S&W revolver is the best on the market, tank-like revolvers not excluded.

After many years of collecting manuals and data one has to ask himself if he intends to make plans to revise his pet handloads downwards yet again next year when the latest reductions in loads are published. My favorite general purpose .38 special load has gone from being less than middle-of-the-road to being excessively hot since I began loading it in the mid-70's. What's all this?

I don't drink the kool-aide of paranoia that pervades everybody about everything from global warming to simple handloading fun. Erich's post is informative and interesting. In trumpeting caution and some outright gloom and doom some holier-than-thou folks are all too willing to play "gotcha" with ol' Erich while smugly preening their egos a bit at the same time.

If someone wants to carefully work up some "hotrod" loads and report their findings I'm all ears. I'm not required to mimic them and anyone who does also likely disregards the warning on the hairdryer and blow dries his hair in the bath.

quote:

Originally posted by Mack Heath:
SAAMI IS the industry.

Mack, you are obviously a very bright fellow with a great deal of experience, education and practical knowledge, which I do appreciate your sharing here. Nonetheless, I can tell you unequivocally that some very much "inside" folks in the ammo makers' industry will disagree vehemently with that statement, which is one I personally once thought to be true, until a big client set me straight. Maybe SAAMI wants to be the industry, and maybe some folks in the industry would agree with you, but that is far from a universal view. In the long run, does it matter? Perhaps not.

quote:

Originally posted by bmcgilvray:
I don't drink the kool-aid of paranoia that pervades everybody about everything from global warming to simple handloading fun. Erich's post is informative and interesting. In trumpeting caution and some outright gloom and doom some holier-than-thou folks are all too willing to play "gotcha" with ol' Erich while smugly preening their egos a bit at the same time.

If someone wants to carefully work up some "hotrod" loads and report their findings I'm all ears. I'm not required to mimic them and anyone who does also likely disregards the warning on the hairdryer and blow dries his hair in the bath.

Ditto, neighbor!