Quote:

---

... Yes - many rounds today list seemingly high numbers, but when you compare those high PSI numbers with the CUP numbers on the same loads, you see the difference. ...

Here's a chart, showing SAAMI pezio PSI and CIP pezio PSI numbers, as well as the SAAMI and CIP 'crusher' #'s.
...
Now, if your handloads are giving you higher speeds than factory ammo, I have to wonder what your loads actually are producing for pressure?

http://kwk.us/pressures.html

---

Thanks for that info and the table, Daryl,
Most of the new, fat cartridges, which often lack CUP figures, seem to be right up there, pressure-wise. Maybe the increased base area* helps spread the back thrust, though years ago I read the situation was better with a smaller head (eg: rebarrelling a SMLE to .30/30). I noted with some disquiet that the back-locked .375 Win pushes 64,000psi - but maybe the large rim area helps there, too.

That calibre at the top of the list, I think, is the 17 Hornet, which could screw the nozzle up a bit.

I know that some of the older calibres are loaded lower for fear they'll be fired in unsafe rifles but the new-calibre pressures still surprise me. This uneasiness is compounded by my own experience with the Tikka 270WSM using factory ammo. One day after the barrel was run in and well-cleaned, I fired about 15 shots, slowly, to find the bolt hard to open on the last shot or two. Supposedly, the industry knows what it's doing but, in an age of plastic bolt shrouds, it doesn't impress me.

As to my own reloads, I never go anywhere near maximum with the 338 as my bush shooting doesn't need taught trajectories. I've only ever chronographed a couple of shots, which registered where expected.

On the opposition forum's tables, though, I noticed some maximum loads for the .30/06 going way over the old 180gr at 2700fps, into 300H&H territory and high pressures. These loads were two grains more than the max in my book from 40 years ago. Unless you're too poor to buy another rifle, why not just get a magnum of some kind for increased power?


*though I notice WSM rims seem to be rebated a bit.

Post Extras