Chamber Pressure

[fknipfer]

If you look at the Marlin's 1885 Rifle they are conservatively rated at  28000PSI/Cup, so are the Shiloh Sharps, all NEF's  (all new rifles no old ones).  Grizzly Cartridges makes the statement on their rounds the the following:
45-70 420gr Hammer Head round is 35000 CUP.
45-70 350gr Woodleigh Weld Core round is 35,000 CUP.

What are the real ratings for these rifles?  All my manuals say keep them to the 28,000 level.  Is this and accident awaiting to happen or are his ratings true?

Garret does say don't use these rounds in any other older or pre-new era rifles. 

I load my rounds to keep them under the 28,000 lever because I really don't like the recoil of such a light rifle like the Buffalo Classic.
Garret make some pretty impressive ammo, but it must be all testing on these rifles in his facility.  It would be nice to have the real pressure ratings on our rifles even if we don't use the higher ratings.

fknipfer

[trotterlg]

PSI and CUP are only vagely related.  There is no way do do a conversion from one to the other.  This comes from different ways of measuring pressure.  Larry

[Lone Star]

Actually, 28,000 CUP = 28,000 psi in the .45-70 - this from Alliant's SAAMI pressure chart.  They are the same.

You clearly need more/different loading manuals!  The Marlin M1895 rifle is not rated at 28,000 cup by everyone:

Hornady.....40,000 cup
Hodgdon....40,000 cup
IMR...........40,000 cup

Speer/Lyman/Accurate...28,000 cup


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