Light load 308 recipe

[semperfidelis354]

I'm a novice reloader but am living my lee turret for my pistol loads and am going to start with 308 very soon

Why am I asking for a light load? Well I have a mas 49 56 and it was re-arsenaled to a 308 from a 7.5 French which I'm told has much less power which leads to some feeding problems. So I want to make light loads that may make feeding happier for my rifle. Any help would be great thanks!!!!

[gorblimey]

This should have what you're looking for and then some.. the Harris Load:

http://yarchive.net/gun/index.html

and also check this out:

https://www.hodgdon.com/PDF/Trail-Boss-data.pdf

[problemchild]

NEVER go below the stated minimum charge weight for a given powder. You can get flashover and blow your face and hands off.

[semperfidelis354]

my questiong may be moot anyway, I was re-reading on my weapon and the chamber pressure of a 7.5 is 40,000 whereas the chamber pressure of a 308 is somewhere in the 52,000 range.

even with the minimum charge I doubt I'd be able to reduce the chamber pressure by that much, or does the charge affect that at all?

[XDRoX]

Is this a bolt rifle or auto?

If it's a bolt rifle and you want a no recoil load, just use Trail Boss. You can literally load anything with TB. But I doubt it will function an auto.

[Sky_DiveR]

Wow, using Trail Boss for 27.1k psi??? Now that is a light load!

[semperfidelis354]

It's an auto rifle. Does the chamber pressure get affected when using a lighter load or am I looking at it the wrong way?

[Bill Steele]

As you reduce powder you reduce chamber pressure of a given load, usually in the .9 to .95 factor for each grain reduced from max, depending on the specific powder and bullet.

The Lee 2nd Edition book has reduced loads for many popular rifle powder and bullet combinations that go well below your 40,000 PSI number. Some as low as 13,000 PSI.

Just look in the cast bullet load section of the book. It has reduced load tables for 308 and 30-06 and the formulas for how to figure pressure and velocities for reduced loads for calibers that are not in his tables.

I am still a little fuzzy on the logic that a lighter load will aid in your rifle's cycling, but you can definitely load your 308 ammo well below 40K PSI.

[semperfidelis354]

Not sure if it will actually help the cycling but I researched the specs on the rifle and what problems it had when rechambered to 308. Since the 7.5 French round generally has a chamber pressure of 40,000 the 308 version increased the pressure by 12,000 since it generally has a chamber pressure of 52,000 (I pulled these numbered from a detailed review of the mas 49 56 308 conversion sorry I don't know the URL). One way to fixe the overpressure problems was to port the barrel I believe, or to instal a pressure regulator on the gun. I would rather not mar the rifle any more than it already has been so I thought making a 308 round with a chamber pressure closer to 40,000 might aide in the longevity of the rifle and possibly cycling problems.


Or I could be dead wrong and just deal with it. This is all brand new stuff to me.

[gorblimey]

I totally missed the little detail of the rifle being semi-auto. Good luck!

[Bill Steele]

Not sure if it will actually help the cycling but I researched the specs on the rifle and what problems it had when rechambered to 308. Since the 7.5 French round generally has a chamber pressure of 40,000 the 308 version increased the pressure by 12,000 since it generally has a chamber pressure of 52,000 (I pulled these numbered from a detailed review of the mas 49 56 308 conversion sorry I don't know the URL). One way to fixe the overpressure problems was to port the barrel I believe, or to instal a pressure regulator on the gun. I would rather not mar the rifle any more than it already has been so I thought making a 308 round with a chamber pressure closer to 40,000 might aide in the longevity of the rifle and possibly cycling problems.


Or I could be dead wrong and just deal with it. This is all brand new stuff to me.

Not knowing the gun, anything I would post on its operation is just speculation.

If you want to try loads at or even well below the 40,000 psi range for your 308, I would pickup a copy of Richard Lee's Modern Reloading 2nd Edition. It has a whole section on reduced loading, and has tables for 30-30, .308 Win and 30-06 with tons of different bullet and powder combinations with resulting pressures. These loadings were verified by Hodgdon's lab for accuarcy (of the resulting pressures and velocities, not shooting accuracy). He includes many popular powders like Vargent and BL-C(2) with various bullet weights, so you can definitely test the operation at much lower pressures than standard load tables.

If you go this route, read the whole section (not that many pages) as while he does not subscribe much to the theories you hear about reduced loading leading to KB's, he does recommend maximum reduction levels of 50% from max for most powders and as low as 20% for the slowest powders like BMG. He includes a table of burn rates and a way to calculate your reduction maximums for each type of pwder.

Finally, once you get going, don't load a ton at any given reduced load. It sounds like a reduced pressure load will cycle you gun fine, but as you go down, you will likely find a cutoff where any lighter loading and the gun will not cycle. I would pick a powder and bullet from the Lee tables for 308 that got me say 10% under 40,000 psi and start there and slowly work up.

Have fun.

[semperfidelis354]

Thanks for the info! I'll be starting the reloadig process when my dies get here. On a side note isnt it nice of people to leave all their pretty and shiny 308 brass all over a range? They make me happy

[CSACANNONEER]

Using lighter bullets will give you a softer load with less pressure too. So, use a light bullet, a minimum load of a slower burning powder and you just may find the load that you're looking for.