Relaoding for M305 .308/7.62x51

[Nate.308]

Hi Gentz,

I have recently acquired my first M305 and would like to reload my own rounds. I am a little confused with the difference between .308 win and 7.62x51. Can I use .308 win in my 305? do I reload to a different specification? I understand this can be a lengthy process to explain so a point in the right direction is all in need. I have been shooting for years but I have never loading any ammo that wasn’t specifically designed for the firearm.

Nate

 

[Pr589]

Load using 308 specifications and do your load work-up as usual. You can tweak your process to best preserve your brass, as you get familiar with your rifle and what it likes.

While the M305 is generously chambered, even for 7.62 - which is longer chambered than 308, this should not pose a danger if you reload to 308 specs. Further, 308 has a higher max pressure than 7.62 but if you perform a normal ladder, you will avoid these issues. I'm sure that others will chime in with the specific differences.

Enjoy the experience, the M305 is quite responsive to different loads.

 

[bigedp51]

The .308 Winchester and the military 7.62 for all practical purposes are loaded to the same chamber pressures. What causes confusion is there are three different methods used for "MEASURING" chamber pressure. BUT all three pressures are the exact same pressure measured three different ways. In reality there is less than 200 psi difference between published figures, and with the addition of new military 7.62 cartridges the chamber pressure is higher in the 7.62x51 military ammunition.

1. Copper crusher known as CUP
2. Transducer method known as PSI
3. European CIP method with pressure measured at the case mouth also in PSI.

Below are the milspec pressure testing requirements for commercial contract 5.56 ammunition made for our U.S. Military. I'm using this data below because I do not have the pressure requirements for the 7.62x51. Please note that both the copper crusher and transducer methods are listed as PSI because pounds per square inch is our American pressure standard.

MIL-C-9963F
15 October 1976
SUPERSEDING
MIL-C-9963E
12 May 1970

MILITARY SPECIFICATION
CARTRIDGE, 5.56MM, BALL, M193

3.7 Chamber pressure.

3.7.1 Measurement by copper-crush cylinder.-The average chamber pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not exceed 52,000 pounds per square inch (PSI). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 58,000 PSI.

3.7.2 Measurement by piezoelectric transducer.-The average chamber
pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not
exceed 55,000 PSI. The average chamber pressure plus three standard
deviations of chamber pressure shall not exceed 61,000 PSI.

Below is everything you need to know.

RELOADING FOR THE MATCH M14 (or cheap Chinese copies)
http://www.zediker.com/downloads/14_loading.pdf

 

[yomomma]

Send me three fired case with the fas valve off. I can give you rough chamber dimensions. If your chamber is on the extreme side I would stick to 7.62. Otherwise .308 is just fine.