Possible error on CUP/PSI correlation?????????

[PJGunner]

I was looking at the CUP/PSI correlation and something does not look right. Compare the pressure figured for the .280 Rem. vs the 7MM Rem. Express.

.280 Rem. 50,000 CUP/60,000 PSI

7mm Rem. Express 40,000 CUP/45,000 PSI.

The .280 Rem. and 7MM Rem. Express are one and the same cartridge with the Express supposedly loaded to slightly higher pressures.
The posted figures for the 7MM Express look more like SAMMI figures for the 7x57 Mauser and even the CUP figure looks a tad low as does the PSI number. I load and shoot both cartridges and the numbers just do not look right to me.
Paul B.

 

[FOTIS]

They are the original postings for the 280 rem (7mm express) . Originally loaded for the rem autoloader. hence the underloaded 280 rem....no longer an issue though. Even in quickload today it is SAAMI rated at under 59K instead of 63 to 65K as it should

 

[PJGunner]

No argument from me on the .280 Being underloaded from the factory. What I question is the 10,000 CUP/15,000 PSI difference when the 7MM Express was loaded to a higher pressure level and the data shows it at a noticeably lower level. That's closer to the 7x57 specs at 45.000 CUP/50,000 PSI. That's why I question it.
Paul B.

 

[Ridgerunner665]

Likely a typo...

 

[MAinAR]

I perfer this ANSI/SAAMI 2015 version as it not only gives pressure ratings in both PSI and CUP on many cartridges but also establishes known velocities with most loadings and bullet weights.....

It list only the .280 Rem and no mention of 7mm Express, anyway has CUP listed as 50,000 and psi at 60,000.

Takes a lil scrolling but run down to about page 22 start and review.

http://saami.org/specifications_and_inf ... ad/206.pdf

 

[PJGunner]

Did a little digging and found that the 7MM Exp. was supposed to be loaded to a somewhat higher level than the original .280. Probably the best I could find with some numbers is from Ken Waters Pet Loads where he did the .280/7MM Exp. together in on article. He choreographed both versions of the cartridge and found the 7MM Exp. was a whole 80 FPS faster than the .280. Methinks they were afraid to bring it up to it's full potential in case people might shoot it in the semi-auto rifles. After all, a few did mistake the 7MM Exp. for 7MM Rem. Mag. with disastrous consequences.
Paul B.

 

[Wis65x55]

What would probably be the maximum CUP/PSI that would probably be safe to push a 280 Remington in a bolt action rifle before problems would start to rear their ugly head?
Keith

 

[Ridgerunner665]

65,000 psi

Same as 270 Winchester.