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The bottom line is I just want to know if my 7x57 shooting a 170 gr bullet will be a better penetrating rifle than my .270 shooting a 150 gr bullet or my .308 shooting a 165 gr bullet.
I wanted a slow and heavy rifle for big time penetration and bought the 7x57 for that, but then saw the SD of the .270 150 gr bullet was right up there past and with the 7x57 bullets and I wondered if the 7x57 was that much of a better penetrator than the .270
That lead to this post.
Simple enough - after all the speculation
You have both rifles - run the real world tests ..
Depending on the type of 7x57 rifle you have and it's age - and chamber ( short throat ?}
You may be able to load it to similar velocities to the 270 ( 6.858mm )
BTW ;
7x57 is not normally considered a slow heavy round
Standard industry loadings for the 7x57 are on the low side due to concerns with very old weapons ( small ring Mausers from before 1900 )
See SAAMI CIP data with max pressure ( will download a PDF file )
C.I.P. Homologation 7x57
CIP Pmax pressure 3,900 BAR = 56.565 PSI ( say 57,000 psi ) SAAMI is 51,000psi
Walter Maitland Dalrymple Bell used a 275 RIGBY ( same thing )
Here is a whole lot about him , his rifles , and the type of bullet he used
WDM Bell & His Elephant Hunting Rifles
Speaking personally, my greatest successes have been obtained with the 7 mm. Rigby-Mauser or .276, with the old round-nosed solid, weighing, I believe, 200 grs. It seemed to show a remarkable aptitude for finding the brain of an elephant. This holding of a true course I think is due to the moderate velocity, 2,300 ft., and to the fact that the proportion of diameter to length of bullet seems to be the ideal combination. For when you come below .276 to .256 or 6-5 mm., I found a bending of the bullet took place when fired into heavy bones.
“Karamojo” Bell on Rifles: In His Own Words
When archive.org is up again you may be able to find his books
Treeman may find some of his answers in the above ?