09-14-09, 20:12...
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I apologize for resurrecting this thread, but I'm researching a retro A1 build and I wanted to understand a bit more about the 1:12 twist rate (vs. the "modern" 1:7 twist rate).
From the information shared here, it seems that the following statement is wrong?
So, 55gr XM193 out of a 14.5" barrel with 1:12 twist rifling goes around ~3000 fps and is spinning at 180,000 rpm according to this RPM calculator:Quote:
"This is important if you're shooting living targets, e.g., hunting because the fragments, combined with hydrostatic shock, tend to produce a much larger and more potentially lethal wound cavity than a bullet that stays in one piece. The relevance to rifling twist is that usually only a very rapidly spinning bullet - say, over 250,000 rpm - will fragment like that. A 1:12 twist won't produce that effect"
https://www.at3tactical.com/blogs/ne...rifling-part-2
http://www.accurateshooter.com/techn...tes-stability/
Same bullet weight, same barrel length, but 1:7 twist rifling and slightly less velocity (~2900 fps) produces ~300,000 rpm.
The difference in RPM only effects the flight path of the bullet, and not the lethality -- right?
For practical understanding that statement still holds true. The simple answer is "barrier blind expanding" and then go train.
I have seen some discussions about higher RPM causing slightly more damage with some bullet designs, I believe fragmenting.