cartridge pressures

Some of you might be confusing pressure units.
PSI and CUP.
My lyman 48th Edition Reloading Handbook lists
max. pressure for 300WSM approx.63000 PSI,
and for 300WM bit over 51000 CUP and bit over 63000 PSI.
Soo in pounds per square inch units pressure is the same.
FYI CUP-Copper units of pressure.
 
farmnut said:
Some of you might be confusing pressure units.
PSI and CUP.
My lyman 48th Edition Reloading Handbook lists
max. pressure for 300WSM approx.63000 PSI,
and for 300WM bit over 51000 CUP and bit over 63000 PSI.
Soo in pounds per square inch units pressure is the same.
FYI CUP-Copper units of pressure.
Click to expand...



Quite the contrary.. the hodgdon manual lists the wsm at approx 64 000 and the 300 win at approx 54 000 with the load data:dancingbanana:
 
All of the above--in a weak action, the action is the limiting factor and in a strong action it is the brass case. A number of years ago you could get cartridge cases with stainless steel heads and brass bodies to get the best of both worlds. Latest issue of Handloader mag has an interesting article on pressure comparison with similar loads between 300 H + H and the 300 WSM.

44Bore
 
bingo1010 said:
Quite the contrary.. the hodgdon manual lists the wsm at approx 64 000 and the 300 win at approx 54 000 with the load data:dancingbanana:
Click to expand...

What units, your numbers mean nothing with out units.
SAAMI maximum average pressure for the 300 WM is 54000 CUP.
And I suspect your 64 000 is in PSI, if that is the case then
you are comparing apples to oranges and getting your self and everyone
confused in the process.
 
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farmnut said:
What units, your numbers mean nothing with out units.
SAAMI maximum average pressure for the 300 WM is 54000 CUP.
And I suspect your 64 000 is in PSI, if that is the case then
you are comparing apples to oranges and getting your self and everyone
confused in the process.
Click to expand...


ALL OF THE ( #'s ) I AM QUOTING ARE PSI:D
 
bingo1010 said:
ALL OF THE ( #'s ) I AM QUOTING ARE PSI:D
Click to expand...
Well then for what ewer reason Hodgdon decided that their max.
load should be less then SAAMI standard.
Maybe the rifle they were using could only handle that much.
Remember the famous reloading manual disclaimer,
"Newer start at max. load. the loads listed were safe in our
rifle, your results may wary, blah blah blah."
 
So why haven't steel casings caught on? Much higher yield strengths than brass, cheaper - all good. And why isn't the steed cased ammo out there loaded to several hundred thousand PSI?
 
CUP is the methodology, but PSI are the units still. With the CUP method, a copper column is squished, then measured and the number of PSI required to deform it are calculated. Nevertheless, CUP measured pressures are usually listed with 'CUP' as the unit, even though strictly speaking, CUP isn't a unit of measurement. Normally, when a pressure is listed in PSI, it's piezo-transducer measured. A peizo transducer produces a graph that is averaged instead of a single measurement like a copper slug. In other words, a piezo-measured pressure can show pressure peaks better than CUP, which is why it's typically higher. PSI (CUP) and PSI (transducer) can NOT be directly compared in an apples-to-apples manner.
 
prosper said:
CUP is the methodology, but PSI are the units still. With the CUP method, a copper column is squished, then measured and the number of PSI required to deform it are calculated. Nevertheless, CUP measured pressures are usually listed with 'CUP' as the unit, even though strictly speaking, CUP isn't a unit of measurement. Normally, when a pressure is listed in PSI, it's piezo-transducer measured. A peizo transducer produces a graph that is averaged instead of a single measurement like a copper slug. In other words, a piezo-measured pressure can show pressure peaks better than CUP, which is why it's typically higher. PSI (CUP) and PSI (transducer) can NOT be directly compared in an apples-to-apples manner.
Click to expand...

cup was the unit devised for pressure comparison before piezo transducers where available and in common use. It provides a useful comparison to other cartridges measured in cup, but is not a linear value, where psi is when measured by transducer.
 
Quite the contrary.. the hodgdon manual lists the wsm at approx 64 000 and the 300 win at approx 54 000 with the load data
Click to expand...

I suggest you take another look at the Hodgdon manual. 300WSM loads are quoted in PSI and 300 Win Mag is in CUP...two very different measurments
 
bingo1010 said:
how can some cart. operate at 45 000 psi others at 55 000 and still others at 65 000, all in the same action and all using the same material( brass ):confused: :confused:
Click to expand...

Brass may be the common denominator but the thickness and hardness of the rear part of the case have a lot to do with the pressure ability. Some brass will withstand a lot more pressure before it begins to deform due to the design and hardness.

Concerning various actions:

Modern bolt action firearms will handle considerably more pressure than older lever action firearms.

So if you have a modern bolt action and an older lever action chambered for the same cartridge, you can handload the shells for the bolt action considerably hotter, safely. If you tried the same load in an older lever action, it would not be able to handle it, very likely blowing up.

I believe factory ammunition limits are based on the strength of the action, so the ammunition will be loaded for the weakest link.

"farmnut" may have had this thought on his mind when he posted his rude reply.
 
guntech said:
Brass may be the common denominator but the thickness and hardness of the rear part of the case have a lot to do with the pressure ability. Some brass will withstand a lot more pressure before it begins to deform due to the design and hardness.

Concerning various actions:

Modern bolt action firearms will handle considerably more pressure than older lever action firearms.

So if you have a modern bolt action and an older lever action chambered for the same cartridge, you can handload the shells for the bolt action considerably hotter, safely. If you tried the same load in an older lever action, it would not be able to handle it, very likely blowing up.

I believe factory ammunition limits are based on the strength of the action, so the ammunition will be loaded for the weakest link.

"farmnut" may have had this thought on his mind when he posted his rude reply.
Click to expand...


Thank you. I guess some people know what they are talking about.
But I don't agree with the first paragraph, I don't think cartridge companies
specify different brass for higher pressure cartridges.
I have reformed quite a few 30-30 cases in to 219 Donaldson Wasp cases,
the wasp is noted for hot loading specially early recipes which I have tried
and the brass strength was newer a issue.
 
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bingo1010 said:
so farmnut what is the explaination for this? since "some people know what they are talking about"
Click to expand...
SAAMI-Small Arms and Ammunition Manufacturers Institution
in their infinite wisdom decided that industry standard for
30-06 be 50000 CUP. You have to talk to then to find out why
and while you are at it ask them why few years ago they lowered the
max. pressure for 22 Hornet by 4000 CUP
 
farmnut said:
SAAMI-Small Arms and Ammunition Manufacturers Institution
in their infinite wisdom decided that industry standard for
30-06 be 50000 CUP. You have to talk to then to find out why
and while you are at it ask them why few years ago they lowered the
max. pressure for 22 Hornet by 4000 CUP
Click to expand...


so these are the people that you refer to as " knowing something"?
 
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