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Old May 3, 2008, 01:59 PM   #1
Tomas
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Some emperical evidence supporting difference in NATO brass vs. "civilian" brass.

I wanted to see how much difference there really was, if any, between NATO (Lake City) brass and "regular" brass (Remington).

So, I loaded up 43 grains of WW 748 in each, under a Nosler 180 solid base bullet and tested them through a Chrony. Rifle is a Weatherby Vanguard .308 Win.

The rounds through the Remington brass averaged 2557 fps. SD 19.9
The rounds through the LC brass averaged 2675fps. SD 23.4

That's over 100fps difference, and the only thing different is the brass. I even alternated rounds fired to eliminate any issue of the barrel heating up affecting velocity.

Temp was 45 degrees, elevation was 1000 ft.

Thought it was an interesting test.

Tom
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Old May 3, 2008, 02:37 PM   #2
wjkuleck
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Thought it was an interesting test.
Really, all you need to do is to do a comparative weigh-in, or a water capacity comparison, to demonstrate that LC will be thicker & thus have less internal capacity than the Remington.

If you want a real difference, throw Federal American Eagle into the mix.

Oh, and less internal capacity = higher pressure = greater velocity.

Regards,

Walt
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Old May 3, 2008, 11:23 PM   #3
Bullet94
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The most important thing to remember about military brass is that the internal capacity will probably be less than commercial .308 Win brass, because military brass often has thicker webs or casewalls. Montana Marine reports his fire-formed milsurp cases hold 56 grains of H20 on average compared to 58 grains for fire-formed Winchester. Given the reduced capacity of military brass, you should reduce posted max loads by 1.5 grains when loading with Lake City or most other milsurp brass. However, the IMI MATCH brass is closer to commercial brass in internal case capacity (ICC). Kevin Beggs reports: "Fired, my IMI Match brass runs with an ICC of 55.0gr and bumping the shoulder back .001" will net me an ICC average of 54.0gr. LAPUA runs an average of 54.4gr and Federal runs an average of 54.3gr ICC."
The above was taken from here -

http://www.6mmbr.com/308win.html


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Old May 4, 2008, 06:24 AM   #4
wogpotter
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It was an interesting test, but not quite for the reasons stated.
For me it confirms the 1 gr difference I usually use for powder charges between .308 & 7.62 ammo. 100fps comes out really close to the data I have for different loadings with the 1 Gr allowance. Thanks.
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