174 gr RN

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 britrifles wrote:

Goosic, is there a typo in the max pressure, 35,440 CUP?
I’ve got an 1950’s article in the NRA Reloading Handbook with IMR 3031 with several bullets including the Sierra 180 spitzer.  Also IMR 4320 and 4350 loads with Remington 215 gr round nose and Norma 216 gr round nose.  

Here’s a some of the results (velocity 20 feet from muzzle):

180 Sierra Spitzer,  3.075” OAL, 42.0 gr 3031, 2533 fps, 44,220 CUP
215 Rem SP, 3.075” OAL, 49.5 gr 4350, 2432 fps, 44,630 CUP
216 Norma SP, 3.075 OAL, 49.0 gr 4350, 2404 fps, 43,400 CUP

Identical loads were pressure tested with the 216 gr Norma bullet with two different cases which gave quite different pressures.  The Remington cases (load above) gave considerably lower pressures than the Norma cases (which gave 47,610 CUP).  Variations in case thickness and hardness can affect pressures.  

These loads are near at or near maximum (one load listed was over 45,00 CUP). 

It is a possibility britrifles that the test was done using US Military pressure tests or the Piezoelectric test. This is taken from one sheet of paper dated 1955 however and was removed from a textbook from Dupont reloading tables using IMR3031 and a .311 174grn MC/MR, military cartridge/military round. The breech pressure using the minimum 37.0grn shows 35,000 and 35,440 using 42.0grns.  I cannot find any more on the subject and the original owner of the sheet of paper who gave it to my shooting buddy who has given it to me, passed away years ago...