Pressure

[DGY]

Good day all, I have a Brno zh304 7x57r over 12 2 3/4, I’m trying to find what are they rated pressure wise, I heard that they are really strong actions, but I would like to have some real numbers if anyone here might have some(no hypothesis numbers please).
I did a bunch of google search and can’t find any numbers! I know lots of rifle chambered in that caliber are in some regular break action guns and they suggest to reload appropriately, I’m just wondering if the ZH series can be reloaded “hotter” more like a 7x57( unrimmed)?
Thanks

 

[Ganderite]

Some American manuals tend to be dumbed down because of the old weak actions still in use.

I use the VHT manual for the full power (CIP) data. That gun will take full power ammo.

 

[Longwalker]

If you want to know the pressure of European cartridges, look at the CIP standards for that cartridge. They will list max. permissible pressure, which should not be exceeded. It will be more than USA lawyer driven SAAMI pressures. But then you must use European load data, not American.
In the U.S., voluntary pressure standards for rifle cartridges are set by SAAMI, a member of ANSI. Most other countries in the world follow the standards of Europe's CIP (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives or Permanent International Commission for the Proof of Small-arms, sometimes referred to as the International Proof Commission).

The piezo measured pressures below are rounded up to the nearest ksi, ie.1000 psi. Note: There is NO 7x57R standard in SAAMI.

7x57: SAAMI 51 CIP 57
7x57R: CIP 49

 

[DGY]

Thank you guys!! Really appreciate it! So CIP at 49 it is for the brass right, cause you could have a gun like a Ruger no1 that could take lots more pressure right? Or I’m missing something(I usually do) !

 

[cosmic]

Well - Except for the rim, the two cartridges are identical. I dont know where you get the impression that the Brno actions are weak. Au contraire, they are more than capable for the intended purpose. I've shot the same gun using 7x57 min book load data, with the bullets seated loonng - the Brno's have long throats. The pressures are so low, they dont fireform the case. I've gone up to within 2 grains of book max (my standard limit), before getting the brass to fireform.
Based upon your previous posts, you're relatively new to reloading. Loading for older cartridges can be bewildering, good luck with your endeavours.

 

[Potashminer]

Thank you guys!! Really appreciate it! So CIP at 49 it is for the brass right, cause you could have a gun like a Ruger no1 that could take lots more pressure right? Or I’m missing something(I usually do) !

Some years ago, USA writer John Barsness did similar thought - he had 9.3x62 in a CZ550, I think. He noticed that the same rifle was available in 30-06, so wondered why he could not load 9.3x62 up to 30-06 pressures. Except for some minor differences, the cartridges are pretty much identical, except for bullet size. He wrote in articles and on 24hourcampfire that these loads were pressure tested at the Western Powders lab in Myles City, Montana, so he was not just "guessing" that his 9.3x62 loads actually did have a MAP of 60,000 psi - same as 30-06. His results were 250 grain Accubond at 2,650 fps (Varget), and 286 grain bullets at 2,475 fps (Big Game), and he knows that they are at or less than 30-06 pressure levels.

I think there is merit, as per at least one CGN poster, that chasing velocity in 9.3x62 might not be ideal - it "earned its bones" at much lower velocities, and the lower velocity might be a reason that it worked so well. I simply have not shot any (or enough) game with the thing to know different. Is maybe a North American thing that "faster is better" - is almost absurd (to some) to suggest that may not be true. I have read enough articles about and by Dr. Don Heath (Ganyana) - he certainly used the 9.3x62 a lot, and was not chasing improvements in velocity - in some articles he discusses what he thinks were better bullets, and better bullet performance, but I do not recall that he thought speed was lacking.

 

[DGY]

Well - Except for the rim, the two cartridges are identical. I dont know where you get the impression that the Brno actions are weak. Au contraire, they are more than capable for the intended purpose. I've shot the same gun using 7x57 min book load data, with the bullets seated loonng - the Brno's have long throats. The pressures are so low, they dont fireform the case. I've gone up to within 2 grains of book max (my standard limit), before getting the brass to fireform.
Based upon your previous posts, you're relatively new to reloading. Loading for older cartridges can be bewildering, good luck with your endeavours.

Thank you, and you are right, I am totally new to reloading, just over a year and less than 100rds I would say! Learning lots with this forum and the help of a friend going by the name of “Why not?” here!!

 

[DGY]

Some years ago, USA writer John Barsness did similar thought - he had 9.3x62 in a CZ550, I think. He noticed that the same rifle was available in 30-06, so wondered why he could not load 9.3x62 up to 30-06 pressures. Except for some minor differences, the cartridges are pretty much identical, except for bullet size. He wrote in articles and on 24hourcampfire that these loads were pressure tested at the Western Powders lab in Myles City, Montana, so he was not just "guessing" that his 9.3x62 loads actually did have a MAP of 60,000 psi - same as 30-06. His results were 250 grain Accubond at 2,650 fps (Varget), and 286 grain bullets at 2,475 fps (Big Game), and he knows that they are at or less than 30-06 pressure levels.

I think there is merit, as per at least one CGN poster, that chasing velocity in 9.3x62 might not be ideal - it "earned its bones" at much lower velocities, and the lower velocity might be a reason that it worked so well. I simply have not shot any (or enough) game with the thing to know different. Is maybe a North American thing that "faster is better" - is almost absurd (to some) to suggest that may not be true. I have read enough articles about and by Dr. Don Heath (Ganyana) - he certainly used the 9.3x62 a lot, and was not chasing improvements in velocity - in some articles he discusses what he thinks were better bullets, and better bullet performance, but I do not recall that he thought speed was lacking.

Thank you sir, I’m always happy when you and Ganderite replies to my reloading questions, I have a lot of respect for you guys opinion and experience!

I’m definitely not chasing speed here I think I would be super happy if I could get 2300-2400fps with 175gn bullets while being hunting accurate!

Same with my 9.3x62 in my Ruger No.1, I settled for a load that gives me around 2400fps with good accuracy and I’m super happy with it and even happier that is what I used to take my Yukon moose this year with!!

Thank you all for the great info!!