quote:

Originally posted by ALF:
Oldun:

My CIP spec was revised 15/05/2002 and is the current one in use.

Alf, Thanks for that.
Do you have the revised figures, if there are any, for the 7x57R?
What is the diff, twixed bar and megapascals?
Thanks

/

Alf That's interesting.
The 7x57R revised pressure is what the 7x57 used to be.
It seems reasonable therefore to assume that my old Vihtavuori data for the 7x57 which are set at 330 MPa (47900 psi) can now be used in modern 7x57R rifles.
Many thanks

quote:

For a 140 gr bullet that would mean a velocity limit of plus minus 2710 fps. Exceding this velocity with a 140 gr bullet likely exceeds the CIP chamber pressure limit as determined by CIP no matter what powder is used.

Alf,

If this is the case, it would seem to put the 130 grain bullet in danger at 3,000 fps. So, just more motivation for me to have it pressure tested. Will post the results when I get round to do it.

Warrior

Hey Warrior
More lies here I see.

quote:

I like mine with a shorter barrel to run through the bush

quote:

the length of my barrel is 600 mm or 23.6".

First the barrel is short then it is standard. Then you accuse Gerard of clairvoyance pretending you did not say it was short.


This "lab" you keep on bragging about. Is this the one in your back yard or the one in your head. So far we only have your hearsay of the results and that is not worth much.

My barrel is shorter than Ray's - he stated that his a 26-inch barrel. You must be still half asleep.

For revision: 23.6 inches are shorter than 26 inches ... just say it 3 times and go back to bed !!!



Warrior

/

quote:

Would I, do I shoot these hot loads, Nope, Dont see the need to, my experience with the 7x57 is that it does fine as it was meant to be, if I want faster, flatter I go to a bigger case.

Alf,
Agreed.
Might I suggest that if any one wants more than the 7x57 has to offer, then try the other European standard the 7x64, it's very good.

quote:

Originally posted by oldun:
Alf That's interesting.
The 7x57R revised pressure is what the 7x57 used to be.
It seems reasonable therefore to assume that my old Vihtavuori data for the 7x57 which are set at 330 MPa (47900 psi) can now be used in modern 7x57R rifles.
Many thanks

I think you may be misinterpreting that badly. I don't know how old your Vihtavuori data is, but it sounds like old CIP standard that was actually derived from crusher, not piezo. CIP doesn't really "change" these max pressures, they're usually just revising them for changes in pressure testing technology. The old CIP standards were stated in BAR derived from crusher. Current CIP standards are stated in BAR, but are from piezo, and they're not at all the same thing.

Yes, pmax for the 7X57R is now 3400 BAR, while the old standard was lower, but max pressure hasn't changed at all, it's just measured with a different yardstick now. Muddy as hell I know, but max loads under the old data will generally remain max loads under the new. No, 7X57 data can't be used in 7X57R rifles, modern or otherwise.
------------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

400
My Vihtavouri data is dated 1997
I understood may be and muddy, most things in between was confusing.

Aha.
I also have some later than 1997 VV data.
In 2006 VV released new data, there are new loads for the 7x57R.
Pressure is not stated, however new x57R loads are listed as being heavier than the 1997 x57R loads with the same powders and being less than 1 grain lower than the 1997 7x57 loads. Ergo my comments about using 1997 7x57 data for 7x57R in a modern 7x57R rifles were not far off the mark.
eg
1997. 7x57 175 grain bullet max load 49.5 gr of N165 velocity 2357 fps
2006 7x57R 175 grain bullet max load 48.9 gr of N165 velocity 2333 fps.
I am not a ballistician but I know tha VV are conservative in their loading data and I doubt the an extra 0.6 of a grain would put a rifle in X57R into a danger.
I am happy to load 7x57R with 175 grain bullets with this new data

/

quote:

Originally posted by oldun:
400
My Vihtavouri data is dated 1997
I understood may be and muddy, most things in between was confusing.

oldun:

I understand that it's confusing. It is to me, too, but I'll try.

As you said in your post, (and which I assume to be correct) SAAMI is 46,000 CUP/51,000 PSI for the rimless. Same pressure, different values because the measurement systems are different - crusher vs. transducer. It's the same with old CIP BAR (crusher, and stated in BAR) and new CIP BAR (piezo transducer, but also stated in BAR). Generally, when CIP converted these, they didn't change the max pressure, they were only trying to restate it from one measurement system to the other, just like SAAMI did.

I don't know what the old CIP pmax was for the 7X57s. I don't have the old tables. Perhaps someone here will know what the old crusher standards were. Current CIP pmax (max pressure) is 3900 BAR/56,565 PSI and 3400 BAR/49,313 PSI for the 7X57 and 7X57R respectively. What I'm saying is - if you're looking at data for the rimless that gives pmax as 47,900 PSI (3300 BAR), then either that data is simply wrong, or it is the old crusher standard. Perhaps there is one, but I'm not aware of any other explanation, and I think it's got to be the latter. Either way, you can't compare it to current standards.

Part of the confusion is in the conversion from metric. For example, assume that the old CIP crusher standard for the rimless was 3300 BAR. The conversion used would have been 3300 X 14.50375 = 47,900 PSI, although it isn't really, because it's crusher. The current standard is 3900 BAR X 14.50375 = 56,565 PSI, which is true PSI, because it's transducer. If that's what the conversion was, it generally doesn't represent any increase in max allowable chamber pressure, it's just a restatement of it from the old measurement system to the new. CIP doesn't usually just haul off and increase max allowable chamber pressure for a cartridge by 8700 PSI.

So, when you say:

quote:

Originally posted by oldun:
The 7X57R revised pressure is what the 7X57 used to be.

That probably isn't true, because I think you may be comparing apples to oranges, and because max pressure generally doesn't change, although the units used to express it do. Therefore, the assumption that

quote:

It seems reasonable therefore to assume that my old Vihtavuori data for the 7x57 which are set at 330 MPa (47900 psi) can now be used in modern 7x57R rifles.

...isn't reasonable because it assumes the unlikely. For a rimmed cartridge being used in a drop down barrel gun, as the 7X57R is intended, I wouldn't make that assumption without a definitive answer.
-----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

quote:

Originally posted by ALF:
CIP have never used copper crushers, their measurements have only been done using Piezo.

Not true, Alf. CIP has been around a lot longer than piezo transducer technology has.
-----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

Hey Warrior

quote:

My barrel is shorter than Ray's - he stated that his a 26-inch barrel. You must be still half asleep.

For revision: 23.6 inches are shorter than 26 inches ... just say it 3 times and go back to bed !!!

Ray has two rifles one with a 26" barrel and one with a 22" barrel. You said you like yours shorter so who is half asleep now? I can just see you running through the bush with your short tube and making a fool of yourself. Running through the bush is your way of hunting???? Caught you out again in a half truth hey?

/

400.
With all due respect, and thank you for attempting to cast light on what is a complex matter, but.
When a powder manufacturer via it's publications state that they have revised loads they have tested in their laboratory, that's what I'll be guided by.
Vihtavouri in their Reloading Guide 2006 state that they have revised loads for et al the 7x57R and that the 175 grain bullet in the 7x57R is ..... see above. That is what I would work up to as a maximum load.
PS,
I've contacted VV asking for information on the pressure of the new 7x57R loads. We await a reply.

/

What flap?
I wish I could understand what people are saying

Warrior

No matter what CIP or anyone else says, it is no problem at all to shoot a 130 at 3000 fps in a modern long throated rifle. My pressure trace shows 64000 psi shooting 139's at 3000 fps in MY RIFLE. Some others that are throated differently will not get to this velocity.

quote:

1997. 7x57 175 grain bullet max load 49.5 gr of N165 velocity 2357 fps
2006 7x57R 175 grain bullet max load 48.9 gr of N165 velocity 2333 fps.

I also don't know what the flap is about. According to the above quote from oldun, the two maximum loads are pretty close for the 7x57 and the 7x57R. The only question I would have, as I always do, is: Is the max load for the 7x57 for military actions or for modern actions?
Peter.

/

Thanks Alf. I was not looking at it from that perspective, but rather the loading of the 7x57R which seems to be "up there" with the plain 7x57. On you proof comments, however, how many countries still require proof marks? I believe that England still does, but I don't believe that the USA does. So, if every firearm does not have to be proof tested, how is assurance given?
Peter.

/

Vapodog and Bartche,
I NEVER quoted a load, much less 82 to 83 grs. of H414 in that caliber!!

Hambarger,
I have owned about 7 or 8 Brno 21s or 22, plus a handful of other 7x57 over the years and they have all had those long throats and they every one shot 130 and 120 bullets...You should TEST that therory, it just does not hold water, its an old wives tale..Some guns may not do it but many will...I am sure that you are aware that many if not all Weatherbys are free bored and they shoot well.


Alf,
I didn't list a load but it was 52 grs and in my 26" tube. Also in the great little long throated Brno Mod. 21 and 22 or Mod. 721 and 722 if you prefer, my all time favorite rifles.