doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure vs. Velocity

A ruptured cerebral aneurysm with subarachnoid hemorrhage........pain that bad Greg?

From the SAAMI Technical Data Sheet: Maximum Average Pressure--is the recommended maximum pressure for loading commercial sporting ammunition. Slightly different words, but it's the same thing the CIP refers to as their standard service pressure.

Found any of those pre-WWI Spanish guns yet, Kyrie? Photos maybe? To include details? I find it interesting that Spain did not even adopt obligatory proof until 1924. And that before things became more "standardized", Spanish makers were in the habit of copying proofmarks from other nations. Might explain why not many of those guns made it out of the country.

Kyrie, before you go MIA again in answering Larry's question regarding the ancient pre-WW1 Spaniards, treat us to an actual photo of a 7-pin 578.

Completely misleading. The Maximum Probable Sample Mean (MPSM) is, � �the maximum expected average pressure that may be observed in the testing of product subsequent to its manufacture �� .

The MAP is the intention; the MPSM is the acceptable reality when a lot is tested prior to release for public sale.

Your problem, gun rag writer, is that you want things to be simple. When they aren�t you just start ignoring facts until it�s simple enough for you.

Anyone who is truly interested in this subject doesn�t need to take my word or Larry�s. The actual facts are published by SAAMI.


Asked and answered. Apparently you didn�t like the answer and would like to pretend the answer never happened. Shrug.

Why? You found enough pics of seven pin 578s when you finally followed instructions and did a query on Google images. Or maybe you're like Larry, and want to pretend you didn't see the results of your own query.

One more time!

One trick pony :-)

I never found one actual photo of a 7-pin 578 -- and you know it. I'm challenging YOU to show us a photo, (and not an illustrator's rendition) of an Arrieta 578 with 7-pin locks. Don't play word games -- PRODUCE! or you're just another phony filled with hot air.

I'm surprised this thread has run this long without someone quoting the Rule of 96 ... or at least the late MM.

Actually, to begin at the end . . . no, you disappeared when I asked for photos, details, etc of those pre-WWI Spanish guns. If you answered, please refer us to that answer. In a previous life, I had to deal with secret writing on occasion. ("Invisible ink".) Maybe that's what you were using, and I just didn't know the formula to use to make it appear. Likewise, another Spanish gun fan (in addition to the above) also raised the 7 pin 578 point.

As for the Maximum Probable Sample Mean . . . you forgot the second half of the sentence to which you referred from the SAAMI technical sheet: " . . . and is NOT intended for use as a loading control point." (Emphasis SAAMI.) Might some loads exceed the target for service pressure? Sure. Also true under CIP rules. But the point is, they're both aiming for a service pressure standard. Which, in the case of the 12ga, is 11,500 psi under SAAMI guidelines--whether it's 2 3/4" or 3". That figure is one that is also the upper limit of pressure figures I find when I look at the Alliant Powder reloading guide. Especially in the case of 2 3/4" reloads, there are very few listed above 11,000 psi. And the reason that proof pressure exceeds service pressure by several thousand psi is to provide an additional safety cushion.

As far as being a "gun rag writer", if you have valuable information to provide to the shooting public, maybe you should try getting yourself published in a gun rag. If you can do a better job backing up your facts than you demonstrate here.