The Firing Line Forums - View Single Post - Results: Shooting 180 grain bullets in a 1:12" 308 Win barrel

Bart B. · December 28, 2012, 01:07 PM

Jimro, when the USN's Small Arms Match Conditioning Unit in San Diego got their first Springfield Armory Garand 1:12 twist barrels chambered for the 7.62 NATO round, first tests showed gas port pressure was too low for reliable cycling with both M80 and M118 match ammo. They drilled them out a few thousandths. The Air Force followed suit.

It was the Air Force (I personally know the Airman who did it) that later developed the 190-gr. load with 44 grains of IMR4320 and shared it with the USN SAMCU for reloading M118 primed cases. It produced much higher port pressure and the port's original size worked well. THE USN SAMCU made some Garands for long range use only without drilling out that gas port. Some shot good enough at 800 through 1000 yards that two or three USN team members made the US Palma Team with them.

December 28, 2012, 01:07 PM	#27
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Jimro, when the USN's Small Arms Match Conditioning Unit in San Diego got their first Springfield Armory Garand 1:12 twist barrels chambered for the 7.62 NATO round, first tests showed gas port pressure was too low for reliable cycling with both M80 and M118 match ammo. They drilled them out a few thousandths. The Air Force followed suit. It was the Air Force (I personally know the Airman who did it) that later developed the 190-gr. load with 44 grains of IMR4320 and shared it with the USN SAMCU for reloading M118 primed cases. It produced much higher port pressure and the port's original size worked well. THE USN SAMCU made some Garands for long range use only without drilling out that gas port. Some shot good enough at 800 through 1000 yards that two or three USN team members made the US Palma Team with them.