loading for 308 Win

Onlyme

Onlyme

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I have been loading pistol rounds for many years, and enjoy the work and results. I am considering loading 308 Winchester and have been reading up on that caliber. I have questions about case volume in reference to case weight, with concern about overpressure. I recently weighed a group of cases marked "308win" and found them to weigh 155 grains to 167 grains. I weighed a group of "762 NATO" cases at 177 grains to 181 grains (smaller sample of cases, hope that is irrelevant). I have read posts that "you should load 762's with less powder because of reduced volume". My concern is that the variance within my 308's is greater that the difference between them and the 762's. Right now I plan to only load the 308's. should I be concerned about the variation in case weight? Thanks
 
In Lyman's 49th edition there is a 7.62/308 section. It doesn't have separate reload data for 7.62 and 308. Some 308 brass is not head stamped with the caliber. I bought a quantity of new 308 Lake City brass which is very good brass and there is no caliber designation on the head stamps.
 
Military brass is heavier and will produce the same pressure with a smaller charge. Segregate mil brass from civilian. Every brass manufacturer uses a different formula so they will act differently and have different neck tension. Your best bet is to make groups that are most alike.
 
This was an outstanding load in LC brass a 168 SMK 40.5 grains IMR 4895, any primer. I set OAL to 2.80 inches in my match barrels. They had short throats. If your rifle does not shoot MOA with this, its not the load. M1a shooters typically ended up with a 168 SMK with 41.5 grains IMR 4895. With a new barrel on a M1a I would go 41.0 grains out to 300 yards, then use 41.5 grs at 600.

If you are using a Krieger barrel, 40.5 grains may be a maximum load. I found tight barrels created more pressure issues than case weight variations. Though, if you are running maximum loads developed in 70 F weather, you will be blowing primers in 90 F. Especially in a Krieger barrel.
 
308 is one of the few I'm adamant about matching headstamp for. They have enough different capacities to make a big difference.
I have a couple other guns that get segregated brass because I want to.
 
It depends on what lengths you want to go to. Identical brass could be purchased each time. Even at that one is at the mercy of the manufacturers tolerances. Or to H2O measure each case. If I were to chase the case volume carrot it wouldn't be by simply weighing each case but by the H2O method.
 
frogfurr said:
It depends on what lengths you want to go to. Identical brass could be purchased each time. Even at that one is at the mercy of the manufacturers tolerances. Or to H2O measure each case. If I were to chase the case volume carrot it wouldn't be by simply weighing each case but by the H2O method.
Click to expand...
We are way down the road on a new guy.... hay new guy, use brass with the same headstamp. When your further down the road we got tons of things to make it more interesting
 
Commercial 308 brass is thinner, and lighter than military brass. Both can be used; both can be very accurate. BUT... you load data is going to be slightly different. Especially as you approach max loads.

Since military brass is thicker, it has less volume for powder. A max charge listed for commercial brass may not even all fit in military brass. But you can still get the same velocity and accuracy with either.

If you are working up loads you can use the same data when starting. But since military brass has less volume it takes less powder to achieve the same pressure and velocity. Once you approach a max load you may find that military brass needs 1-2 gr less powder to achieve the same speeds as commercial brass.

This is one of those times where a chronograph is a good thing to have. For example, load data may say 46 gr of powder gives 2800 fps with commercial brass. But in military brass you may reach 2800 fps with only 45 gr of powder. If you can even get 46 gr in the case, you may have an overloaded round with military brass, and some commercial brass.

I separate my brass by headstamp and load in batches. For example, I may use only Remington brass for one batch. Winchester for another and Hornady for a 3rd. Based on my experience I can use the same load data with all of them. Federal brass however requires me to come up with a different load, with lower powder charges to get the same speeds.

I just don't use military brass anymore. Nothing wrong with it other than having a slightly different load. But I have several hundred pieces of commercial brass at this point, and it just makes things simpler for me.
 
Bfh_auto said:
308 is one of the few I'm adamant about matching headstamp for. They have enough different capacities to make a big difference.
I have a couple other guns that get segregated brass because I want to.
Click to expand...

AJC1 and I have had discussions about .308 brass weight in particular... and .308 is probably The One cartridge case that is completely wheels off as far as case weight, volume, and brass composition. He has documented a fairly large difference between in brass with the same headstamps.... enough that I've taken notice of what I'm loading. I've seen commercial brass as heavy as military brass, and vice versa. I don't do volumetric measures, so I don't know if that translates to significant differences in case volume, but, again, I've taken a slightly different path for loading .308, and particularly when I'm pushing the edge of data.

OP, what it boils down to is... keep the military brass separate from the commercial brass. Try to separate the headstamps into a big enough group for you to load for your purpose, which will help maintain consistency. If you are wanting to, as I say, explore the edges of published data, you will need to come up with a separate lot of brass for that purpose, in the quantity you wish. For general reloading, you should be OK sticking with one or two headstamp groups.

General rule of thumb for military brass is to drop 1grn powder when moving from commercial brass to military brass, although I think it's better to drop 2grn and work back up with a short ladder. Safety first.
 
Charlie98 said:
AJC1 and I have had discussions about .308 brass weight in particular... and .308 is probably The One cartridge case that is completely wheels off as far as case weight, volume, and brass composition. He has documented a fairly large difference between in brass with the same headstamps.... enough that I've taken notice of what I'm loading. I've seen commercial brass as heavy as military brass, and vice versa. I don't do volumetric measures, so I don't know if that translates to significant differences in case volume, but, again, I've taken a slightly different path for loading .308, and particularly when I'm pushing the edge of data.

OP, what it boils down to is... keep the military brass separate from the commercial brass. Try to separate the headstamps into a big enough group for you to load for your purpose, which will help maintain consistency. If you are wanting to, as I say, explore the edges of published data, you will need to come up with a separate lot of brass for that purpose, in the quantity you wish. For general reloading, you should be OK sticking with one or two headstamp groups.

General rule of thumb for military brass is to drop 1grn powder when moving from commercial brass to military brass, although I think it's better to drop 2grn and work back up with a short ladder. Safety first.
Click to expand...
Totally agree. I have less variance in volume in 300 WM. Even though it's substantially bigger. Even with it I still use one lot of brass at a time.
 
Charlie98 said:
AJC1 and I have had discussions about .308 brass weight in particular... and .308 is probably The One cartridge case that is completely wheels off as far as case weight, volume, and brass composition. He has documented a fairly large difference between in brass with the same headstamps.... enough that I've taken notice of what I'm loading. I've seen commercial brass as heavy as military brass, and vice versa. I don't do volumetric measures, so I don't know if that translates to significant differences in case volume, but, again, I've taken a slightly different path for loading .308, and particularly when I'm pushing the edge of data.

OP, what it boils down to is... keep the military brass separate from the commercial brass. Try to separate the headstamps into a big enough group for you to load for your purpose, which will help maintain consistency. If you are wanting to, as I say, explore the edges of published data, you will need to come up with a separate lot of brass for that purpose, in the quantity you wish. For general reloading, you should be OK sticking with one or two headstamp groups.

General rule of thumb for military brass is to drop 1grn powder when moving from commercial brass to military brass, although I think it's better to drop 2grn and work back up with a short ladder. Safety first.
Click to expand...
Would you believe I found a high and low group with Norma. :) coincidently there is a high 16x and a low to mid 17x group.
 
AJC1 said:
Would you believe I found a high and low group with Norma. :) coincidently there is a high 16x and a low to mid 17x group.
Click to expand...

I think Norma ammunition is pretty good, I never really considered their brass that good. If I was going to blow it out on brass, I'd buy Lapua. In fact, when I finally wear out my 300cs lot of RP brass in my Savage, which might be a while... it's doing really well... I'mma pick up 200 Lapua cases and continue the chase.
 
Onlyme said:
Thanks for all the input, friends, especially AJC1
I plan to use Hornady Interlock 165gr SPBT for hunting and target (consistency). I will be loading to the lower half of the table in my Sierra manual.
Tikka T3
Click to expand...
If your looking for range pickups federal FC headstamp is everywhere and making a pile of 100 should be easy. The primer pockets is the weak point so they will be gone in 3 or 4 loadings if you go max. If your struggling to find some ill forward you 100 for the cost of shipping.
 
I separate 7.62 brass and 308 brass. I have a batch of 7.62 brass with its own load and bullet.

I have also adopted the policy of using Hornady data with Hornady bullets after some unpleasant issues with using other sources. If that isn’t available I look for data published with hornady bullets used in the load. For handguns I don’t necessarily follow this rule but in my 308 I certainly do now.

For example I used Hodgden data from their website with a Hornady 168 grain Amax. Hodgden doesn’t list that bullet but does list the 168 grain Sierra Match King. I had significant pressure signs and Hodgden listed another 2 grains of powder before reaching max. Hornady’s max was about 0.3 grains below what I was loading when I had trouble.

Later I used Shooters World powder and they publish data using an Amax bullet. No problems and I found a good load with no surprises.
 
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