Sierra Tech Support
 

I had some questions between the load data that Sierra has and Hodgdon. so I called Hodgdon and they said that Sierra doesn't use pressure or pressure barrels. thats hard for me to believe. How can you put out data with no pressure?

RE: Sierra Tech Support
 

Maybe you should check with Sierra to see what they say and get a better explanation of no pressure if it’s true.:eek:

RE: Sierra Tech Support
 

Hodgdon was right. They don't use SAAMI spec pressure barrels. They use regular ole guns. And examine primers, and extractor marks and bolt lift. Just called them.

Thats the reason edition 5 Sierra manual says 43gr max Varget with 140gr 7mm gameking for 7mm08 and edtion 4 says 44.6gr.

Thats a huge variation. But I see the pros and cons.

Pros: True no gun shoots alike and all load data is just guidelines of what one guy saw in one gun. So Sierra may be one to something.

Cons:A pressure barrel are usually much more consistent and may build pressure quicker than a regular old hammer forged barrel from remington. I said maybe, cause so many variations to affect this from thoat dimensions to copper build up. So load data got from a pressure barrel seems conservative and if you follow it, you should be safe any any gun. I said should.

Reading pressure is an art, not an exact science. for instance before you see flattening primers on a CCI primer, you might see a pin hole on it, and be in very high pressures. But a federal will flatten out at middle loads.

RE: Sierra Tech Support
 

Ok I can see from what you posted that I’m confused. So could you explain a couple of things? I understand the part of the forged barrel being used for testing but what is a pressure barrel. - Is this a barrel that is placed in a cylinder and under pressure so that it’s consistent all the way thru?

What is SAAMI . It must be abbreviated for something but what does it mean? I’m a little green when it come to these terms. OK OK I’m very green.:eek:

RE: Sierra Tech Support
 

A pressure barrel is a special barrel companies have that sometimes have a hole in it near the chamber where they used to put copper. Thats where you get CUP from. Copper under pressure. The chambers are supposed to be min SAAMI spec. Wiseman, Kreiger, several others, make these.

Alot of companies use Peizo transduces to measure pressure. And this is PSI or whatever unit of pressure they want to use. But to do this they have to have a baseline and this ammo usually is from SAAMI. Once the baseline pressure is known, they can get to work. This transducer is mounted many ways. Over the barrel, around the barrel and the poor mans way is attached to the brass. Powder companies can also test case rupture with a pressure barrel. This is more or less proof testing. Transducers are used everywhere, from your scales for wieghing powder to cause Aucoustic Wave Guides in channeling fiber optic light (my specialty :D) to making alarm noises.

SAAMI is Sporting Arms and Ammuntion Manufacturing Int. They set most of the pressure standards for most calibers in production. They have min and max specs for about everything concerning the chamber sizes from headspace, to trim length. If a manufacture is SAAMI compliant they agree to ahere to their specs when established when chambering a cartridge.

RE: Sierra Tech Support
 

A little more complicated then I thought but very interesting. Thanks for the info.

RE: Sierra Tech Support
 

Actually I believe CUP is copper units of pressure. Of course thats picking nits....