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6.5x55 50000CUP data limit
- Thread starter Nathan
- Start date
CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
CUP is not psi. 60,000 CUP would likely be around 70,000 psi. Not proof pressure, but getting up there and bound to wear a throat out.
The current SAAMI standard calls for 46,000 CUP maximum average pressure by copper crusher and 51,000 psi maximum pressure by the conformal type piezoelectric transducer. The CIP standard for the channel type piezoelectric transducer is 3800 Bar or 55,114 psi, which Vihtavouri powders will use as the limit in their load data. These pressure limits are likely a nod to the fact a lot of the 1896 Mausers are getting pretty long in the tooth. Your Ruger should be able to take more if the brass holds up OK.
There are several ways to estimate it for the Ruger, but buying and calibrating a Pressure Trace is the best approach. Figure that with many rifle powders a very crude guess is that since your pressure ratio target is 60/51 you can probably increase the charge weight by about the square root of that or around 8.5% to get from a standard load to your objective, but the cases may limit the matter, so work up slowly while watching for pressure signs.
CUP is not psi. 60,000 CUP would likely be around 70,000 psi. Not proof pressure, but getting up there and bound to wear a throat out.
The current SAAMI standard calls for 46,000 CUP maximum average pressure by copper crusher and 51,000 psi maximum pressure by the conformal type piezoelectric transducer. The CIP standard for the channel type piezoelectric transducer is 3800 Bar or 55,114 psi, which Vihtavouri powders will use as the limit in their load data. These pressure limits are likely a nod to the fact a lot of the 1896 Mausers are getting pretty long in the tooth. Your Ruger should be able to take more if the brass holds up OK.
There are several ways to estimate it for the Ruger, but buying and calibrating a Pressure Trace is the best approach. Figure that with many rifle powders a very crude guess is that since your pressure ratio target is 60/51 you can probably increase the charge weight by about the square root of that or around 8.5% to get from a standard load to your objective, but the cases may limit the matter, so work up slowly while watching for pressure signs.
"...caliber seems somewhat limited..." Nope. The 6.5 x 55 has been filling Swedish freezers with moose meat for eons. It'll kill any game you care to hunt with a 140 grain bullet. And Max loads run 4 to 5,000 CUP below 50,000 CUP.
That 50,000 CUP is 4,000 CUP above the SAAMI Max pressure for the 6.5 too. So you will not find 55,000 or 60,000 CUP data.
There is no comparison or mathematical conversion formula for CUP and PSI. They're simply different methods of measuring pressure. Hardest part is the assorted manuals and manufacturers like Hodgdon, use both. It is NOT something you should even think about guessing at either.
That 50,000 CUP is 4,000 CUP above the SAAMI Max pressure for the 6.5 too. So you will not find 55,000 or 60,000 CUP data.
There is no comparison or mathematical conversion formula for CUP and PSI. They're simply different methods of measuring pressure. Hardest part is the assorted manuals and manufacturers like Hodgdon, use both. It is NOT something you should even think about guessing at either.