Please explain this ballistics plot to me


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wacki
October 5, 2013, 02:03 AM
I don't understand the combat divergence. Why is a 20" drop OK but 30" means "combat divergence"? To me it's just a simple

20" = aim for the head, hit the belly.
30" = aim just above the head, hit the belly

http://i42.tinypic.com/pu6wh.jpg

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rcmodel
October 5, 2013, 02:06 AM
Looks to me like a chart some Dumas was trying to use to prove the 6.5 Grendal is a better round then the 7.62 NATO.

He still has some more cyphering to do to prove that!!

rc

wacki
October 5, 2013, 02:09 AM
Just found the original post (http://thefiringline.com/forums/showpost.php?p=4927004&postcount=20). I found the image on arfcom via a random google image search.

Inebriated
October 5, 2013, 03:13 AM
I'm going to make two assumptions, that the graph is mainly concerned about:
1) Precision rifles, with precision optics (referencing the M14 in the post on TFL).
2) Killing living things, not just putting holes in paper (referencing the hunting and combat divergence).

So it seems that we're talking about the M14 in a designated marksman role... For that, energy transfer means a lot more than a slightly-flatter drop. I'll take .308 all day, every day.

EDIT - and looking at Hornady's factory loads, the 123gr AMAX 6.5 Grendel has 51" drop, and 881 ft./lbs. at 500 yards. The 178gr BTHP .308 has 44" drop, and 1554 ft./lbs. at 500 yards. Both reportedly from 24" barrels. So at least with those two, the .308 has the edge in every category, other than recoil

gotigers
October 5, 2013, 07:31 AM
I agree the .308 is a better choice overall. A little off topic, but if you want to get the most out of an AR15, the 6.5 grendel will fit in an AR15, but you would need an AR10 for the .308. Just a thought.

Uncle Mike
October 5, 2013, 03:57 PM
Looks to me like a chart some Dumas was trying to use to prove the 6.5 Grendal is a better round then the 7.62 NATO

Oh yea, and this just goes on, and on and on....

The Grendle is a fine cartridge, but better than the 7.62x51...no!:banghead:

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