Thread: .308 vs .30-06
View Single Post
Old November 16, 2012, 11:53 AM   #45
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,409
Brian, thanks for a decent comparison using QuickLoad. While it's based on known component behavior and predictions on results, it's a lot better than two barrels with unknown internal dimensions and other unknown variables.

Here's more reasonable comparisons between these two cartridges:

MIL-SPEC data for the 7.62 NATO M80 round, 22 inch test barrel:
WC846 powder, 146 grain bullet, 2750 fps at 78 feet
peak pressure 50,000 CUP

SAAMI spec for the .308 Win. round, 24 inch test barrel:
150 grain bullet, 2800 fps at 12.5 feet
peak pressure 52,000 CUP

MIL-SPEC data for the 30 caliber M2 round, 24 inch test barrel:
4895 powder, 150 grain bullet with 2740 fps at 78 feet,
peak pressure 50,000 CUP

SAAMI spec for the .30-06, round, 24 inch test barrel:
150 grain bullet, 2900 fps at 12.5 feet
peak pressure 50,000 CUP

MIL-SPEC data for the 30 caliber M72 round, 24 inch test barrel:
4895 powder, 172 grain bullet with 2640 fps at 78 feet, 24 inch test barrel
peak pressure 50,000 CUP

MIL-SPEC data for the 7.62 NATO M118 round, 22 inch test barrel:
4895 powder, 172 grain bullet with 2640 fps at 78 feet
peak pressure 50,000 CUP

SAAMI spec for the .30-06, round, 24 inch test barrel:
168 grain bullet, 2790 fps at 12.5 feet
peak pressure 50,000 CUP

SAAMI spec for the .308 Win. round, 24 inch test barrel:
168 grain bullet, 2670 fps at 12.5 feet
peak pressure 52,000 CUP

Please, fellas (Art Eatman?), do not get the older copper units of pressure (CUP) confused with the modern piezo transducer strain gauges measuring actual pressure in pounds per square inch (PSI). Shame, shame on both the military and commercial folks using PSI for their pressure numbers when they measured those little primer-size crushed copper pellets' thickness from the piston in the pressure test barrel crushing them, then compared the measurement to a tarage table supplied with each lot. They're not the same actual pressure except in about 30,000 units of each. For these two cartridges, the actual pressure in pounds per square inch is a few to several thousand more than the CUP numbers listed. For example, in the SAAMI loads above at 52,000 CUP for the .308 Win., the strain gauge numbers are 62,000 PSI for peak pressure.

Study the pressure measuring information in the following SAAMI document for both the .30-06 and .308 Win. rounds as well as how each is done:

http://www.saami.org/specifications_...wnload/206.pdf

Last edited by Bart B.; November 16, 2012 at 05:19 PM.
Bart B. is online now  
 
Page generated in 0.05394 seconds with 7 queries