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Rifles, Reloading, Optics, Equipment
Reloading
.270 Win + RL26 = Holy Cow
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<blockquote data-quote="MT Southpaw" data-source="post: 2086371" data-attributes="member: 96292"><p>I too am curious what his max charge was. Here is an article I read that first tipped me off that I might need a faster twist. If you do the formula with the 150 Accubond LR (length of 1.390) it shows a twist rate of 1:8.2, assuming the formula is correct. </p><p>Now I will say that in my dad's stock Savage 270 win we did find a decent pattern with 150 Accubond LR and 59.5gr RL26 which was a little over 3000 fps, I didn't measure the exact distance but it was sub MOA. So it is possible to get a decent pattern with a 1:10 twist, I just assumed that if you really push it for speed it needs a faster twist.</p><p></p><p>"The original article was in the January issue of American Rifleman on page 30. It credits a Sir George Greenhill with developing the formula T x L = 150 for estimating the proper relationship of bullet length to barrel twist. This looks really simple until you find out that the L is the length of the slug in bullet diameters, not in inches & T is the twist of the barrel in bullet diameters, not inches. Since they didn't take the time to convert the formula into inches, I will do it here so that we can all have numbers to look at that actually mean something to us. I'll leave the algebra derivations out unless someone wants me to post them, but this is what it comes down to: The proper Twist in inches = 150 x caliber diameter x caliber diameter / Length of bullet in inches</p><p>Or for a .224 diameter bullet that is 3/4 (.75) of an inch long</p><p>Twist in inches = (150) x (.224) x (.224) / (.75)</p><p>Twist = a shade over 10 (or 1:10) Also</p><p>The proper bullet length in inches = 150 x caliber diameter x caliber diameter / Twist in inches"</p></blockquote><p></p>
[QUOTE="MT Southpaw, post: 2086371, member: 96292"] I too am curious what his max charge was. Here is an article I read that first tipped me off that I might need a faster twist. If you do the formula with the 150 Accubond LR (length of 1.390) it shows a twist rate of 1:8.2, assuming the formula is correct. Now I will say that in my dad's stock Savage 270 win we did find a decent pattern with 150 Accubond LR and 59.5gr RL26 which was a little over 3000 fps, I didn't measure the exact distance but it was sub MOA. So it is possible to get a decent pattern with a 1:10 twist, I just assumed that if you really push it for speed it needs a faster twist. "The original article was in the January issue of American Rifleman on page 30. It credits a Sir George Greenhill with developing the formula T x L = 150 for estimating the proper relationship of bullet length to barrel twist. This looks really simple until you find out that the L is the length of the slug in bullet diameters, not in inches & T is the twist of the barrel in bullet diameters, not inches. Since they didn’t take the time to convert the formula into inches, I will do it here so that we can all have numbers to look at that actually mean something to us. I’ll leave the algebra derivations out unless someone wants me to post them, but this is what it comes down to: The proper Twist in inches = 150 x caliber diameter x caliber diameter / Length of bullet in inches Or for a .224 diameter bullet that is 3/4 (.75) of an inch long Twist in inches = (150) x (.224) x (.224) / (.75) Twist = a shade over 10 (or 1:10) Also The proper bullet length in inches = 150 x caliber diameter x caliber diameter / Twist in inches" [/QUOTE]
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.270 Win + RL26 = Holy Cow
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