35 Whelen
Member
It seems more and more there are discussions on this forum regarding the pressure limitations of older Mauser rifles. Lately, there have been a few discussion centered around the 1916 Mauser, the fact that many are available chambered in such relatively high pressure rounds as the .308 Winchester, and the supposed "facts" that this type Masuer actions is a ticking time bomb when so chambered.
The most regurgitated internet "fact" is that the 7x57mm cartridge is rated by SAAMI ( Sporting Arms and Ammunition Manufacturers' Institute ) at 46,000 CUP or about 51,000 PSI (There's no way to convert CUP to PSI or vice versa).
When I see these "facts" posted by supposedly informed individuals, I can't help but wonder how many people realize that the 7x57 is about 34 years older than SAAMI (Est. 1926) and how many realize that said cartridge is of European descent? In other words, pressures for the cartridge were established LONG before SAAMI was founded and decided that said 7x57mm cartridges loaded on American soil should be limited to 46,000 CUP. I also wonder how many Mauser and Mauser cartridge experts have heard of "CIP"?
CIP (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives )is the European equivalent of SAAMI. I'll not go into great detail about them as there's plenty of resources on the 'net. But to get to the point...
There's an excellent write-up, with non-internet references, on Wikipedia. Here's an excerpt(pay special attention to the last sentence):
"According to the official C.I.P. guidelines the 7×57mm case can handle up to 390 MPa (56,564 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. By contrast, the American industry association SAAMI specifies a lower maximum pressure of 46,000 CUP or 51,000 psi.[4] Although this lower specification is in deference to the purportedly weaker actions of the older Mauser 93 and 95 rifles which are still in circulation,[4] this concern is misplaced, as the original ammunition developed for, and issued with, the M93 Spanish Mauser produced an average pressure of 50,370 CUP in those rifles.[5] [6]"
Hmm....kinda goes against the accepted internet forums info, eh?
Likewise, regarding the 6.5x55:
"The CIP MAP for the 6.5 × 55 is 380 MPa (55000 PSI). SAAMI MAP for this cartridge is 46,000 CUP or 51000 PSI.[2] All Swedish Mauser actions were proof-tested with a single 6.5 × 55mm proof load developing approximately 55,000 CUP (66,000 psi).[3]"
Now, where did the rumor start that the older Mauser actions, ESPECIALLY the '96 Swedish Mauser, was designed for a 46,000 CUP cartridge?
For those of you that are handloaders, it doesn't take much research and extrapolation into the original loadings of either of these cartridges to realize that in order to obtain the ballistics they obtained, especially with the limited powders of 80 or so years ago, (remember, in the early part of the 20th Century, slow burning powders such as 4350's and 4831's had yet to be developed) the loads HAD to exceed SAAMI's 46,000 CUP.
Just a little food for thought...
35W
The most regurgitated internet "fact" is that the 7x57mm cartridge is rated by SAAMI ( Sporting Arms and Ammunition Manufacturers' Institute ) at 46,000 CUP or about 51,000 PSI (There's no way to convert CUP to PSI or vice versa).
When I see these "facts" posted by supposedly informed individuals, I can't help but wonder how many people realize that the 7x57 is about 34 years older than SAAMI (Est. 1926) and how many realize that said cartridge is of European descent? In other words, pressures for the cartridge were established LONG before SAAMI was founded and decided that said 7x57mm cartridges loaded on American soil should be limited to 46,000 CUP. I also wonder how many Mauser and Mauser cartridge experts have heard of "CIP"?
CIP (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives )is the European equivalent of SAAMI. I'll not go into great detail about them as there's plenty of resources on the 'net. But to get to the point...
There's an excellent write-up, with non-internet references, on Wikipedia. Here's an excerpt(pay special attention to the last sentence):
"According to the official C.I.P. guidelines the 7×57mm case can handle up to 390 MPa (56,564 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. By contrast, the American industry association SAAMI specifies a lower maximum pressure of 46,000 CUP or 51,000 psi.[4] Although this lower specification is in deference to the purportedly weaker actions of the older Mauser 93 and 95 rifles which are still in circulation,[4] this concern is misplaced, as the original ammunition developed for, and issued with, the M93 Spanish Mauser produced an average pressure of 50,370 CUP in those rifles.[5] [6]"
Hmm....kinda goes against the accepted internet forums info, eh?
Likewise, regarding the 6.5x55:
"The CIP MAP for the 6.5 × 55 is 380 MPa (55000 PSI). SAAMI MAP for this cartridge is 46,000 CUP or 51000 PSI.[2] All Swedish Mauser actions were proof-tested with a single 6.5 × 55mm proof load developing approximately 55,000 CUP (66,000 psi).[3]"
Now, where did the rumor start that the older Mauser actions, ESPECIALLY the '96 Swedish Mauser, was designed for a 46,000 CUP cartridge?
For those of you that are handloaders, it doesn't take much research and extrapolation into the original loadings of either of these cartridges to realize that in order to obtain the ballistics they obtained, especially with the limited powders of 80 or so years ago, (remember, in the early part of the 20th Century, slow burning powders such as 4350's and 4831's had yet to be developed) the loads HAD to exceed SAAMI's 46,000 CUP.
Just a little food for thought...
35W