Hornady manual question..

[tcoz]

In looking at the .308 Service Rifle data in the Hornady manual I saw that the case used is Hornady/Frontier. Am I correct in assuming then that the data is for commercial cases only and starting loads should still be reduced by a grain or two if using military cases?
I was initially thinking that the data would be for military cases since it was in the Service Rifle section but I guess not.

 

[Blue68f100]

That is just what they used in their test. Start at the min and work you load up. Doing this brass mfg will not matter. You will find that some brands of brass are more consistent than others.

 

[ArchAngelCD]

Even if your cases had less capacity than commercial cases that would not effect the starting charge, only the max charge.

Not all military cases have less capacity than commercial cases. You should check yours before you make and assumptions. They say to use water but I use a ball powder instead. I fill the commercial case with fine ball powder and then pour it into the military case. If it overflows or not I have my answer. (I have H335 available)

 

[Bart B.]

I have never liked case water capacity as the "standard" for its capacity. Depending on its dimensions and shape, the capacity will change.

Its weight does not change. Sort cases by weight. A 1% to 2% spread is good enough for match rifles. More for all others. A long used standard for powder charge change for case weight change is 7/10ths grain charge drop for every 10 grains of case weight increase.

 

[ArchAngelCD]

I have never liked case water capacity as the "standard" for its capacity. Depending on its dimensions and shape, the capacity will change.

Its weight does not change. Sort cases by weight. A 1% to 2% spread is good enough for match rifles. More for all others. A long used standard for powder charge change for case weight change is 7/10ths grain charge drop for every 10 grains of case weight increase.

I did not know that, thank you.

 

[tcoz]

I have never liked case water capacity as the "standard" for its capacity. Depending on its dimensions and shape, the capacity will change.

Its weight does not change. Sort cases by weight. A 1% to 2% spread is good enough for match rifles. More for all others. A long used standard for powder charge change for case weight change is 7/10ths grain charge drop for every 10 grains of case weight increase.

Now THAT is good to know. It'll take some of the guesswork out of it.

 

[Bart B.]

I knew one person who measured case capacity the correct way that eliminates the shape and dimension variables. He cut the top off a full length sizing die such that when in his press full into it, the case neck stuck out the top about 1/16". He used new cases without powder residue that might absorb water. Their empty weights were recorded. All cases pushed full into that die had the same outside shape and dimensions. The only variable was case wall thickness and their powder space volume then varied by those alone.

Cases were filled with water that was mixed with a wetting agent. Cases were pulled carefully out of the die then slid out of the shell holder then weighed. Each case weight was subtracted and the result was case capacity in water.

Weights of 308 and 7.62 cases I've measured range from 149 grains (Western Ctg Co, 1958 match) to 185 grains (CBC, unknown year). Here are others:

Winchester at 157.13, Winchester nickel plated at 159.82, Hornady Match at 166.29, PPU at 166.94, Federal 308 WIN at 176.90, Lake City NM 68 at 177.55, Lake City Match 91 at 177.98, Lake City Match 77 at 178.45, GFL at 178.89, WCC at 179.48, PMC at 179.50 and CBC Nato 12 at 183.09.

 

[Walkalong]

I have never liked case water capacity as the "standard" for its capacity. Depending on its dimensions and shape, the capacity will change.

Its weight does not change. Sort cases by weight. A 1% to 2% spread is good enough for match rifles

Nice to hear, I get bashed sometimes for always talking about case weight and not water volume.

 

[Offfhand]

I get bashed sometimes for always talking about case weight and not water volume.

Mr. Walkalong, do the "bashers" claim that their groups measure in the .1's when they measure cases by volume but only in the .2's when measuring by weight? Be sure to ask them next time.

 

[Walkalong]

lol,.

 

[Bart B.]

Regarding group sizes without knowing how cases were managed, sorted and sized, the NBRSA record data shows the best of five, 5-shot group aggregate record is 0.2238 MOA across 100, 200 & 300 yds Some of the individual groups are in the threes; maybe bigger. Of course, some groups are in the ones and even a couple in the zeros. Therefore, in my mind, that record was shot with a 3/10ths MOA rifle and ammo; that's where all the fired shots went.

 

[Walkalong]

a 3/10ths MOA rifle and ammo

And shooter.