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Posted: 3/29/2009 6:04:03 AM EDT
I have searched, and don't see exactly what I am looking for.
Any reason light weight bullets - 55gr - will not adequeately stabilize in a 1:9 and 1:7 twist barrel? Also, What about 1:9 twist and heavier bullets - 62, 69, and 75 grain bullets. Thanks. |
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I have searched, and don't see exactly what I am looking for. Any reason light weight bullets - 55gr - will not adequeately stabilize in a 1:9 and 1:7 twist barrel? Also, What about 1:9 twist and heavier bullets - 62, 69, and 75 grain bullets. Thanks. 55-62 gr will stabilize in a 1:9 twist barrel, a 1:7 will stabilize 55gr-75gr. |
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my box of hornady 68 gr match bullets says they are good for 7-10 twist
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All of my barrels are either 1:9 or 1:7. The heaviest I shoot are 68 grain and that's fine with both twists as is 55 grain.
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Tons of posts concerning this. Most barrels will shoot 55-69 gr. quite well. 1/7 is better for things 70 gr. and above.
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Biggest factor to determine the proper twist to stabilize a bullet is the length of the bullet. BUT, since the bullets has to be the same diameter and most are the same basic profile, the length will vary pretty darn close to directly with the length. SO, the gouge you hear is still correct.
I believe the gouge is close to this: 1/9 twist, 55-62gr 1/7 twist, 62-85gr The most accurate would be to put the exact amount of spin needed on the bullet, if you can't have that, then more spin is usually better than less spin. I think factors like how balanced or how consistent the bullet is made will affect how well it stabilizes with a certain twist. i.e. those that say that Hornady bullets stabilize in their barrel that supposedly has to little twist to stabilize it. Speed of the bullet as well, so some rounds may have a different muzzle velocity and stabilize better with a certain twist than others. I think, don't really know, the only time to much spin hurts a bullet is far out, near the end of its ballistic arc (long range). Might be why you see folks talk about their 1/7 barrel shooting 55gr just great, because at most plinking ranges, even mid range target shooting, that extra spin isn't hurting. You'll get a dozen different opinions, many will tell you their 1/7 barrels shoot everything perfect, others will tell you they get the most accuracy with the barrel that has a twist closest to the gouge for the weight of bullet they are shooting, other will say the same, but they have found a few exceptions where they can shoot one brand/type of round that is lighter/heavier than the gouge. Like anything with a design, the parameters you select are often a compromise to best cover the conditions you'll use the design in. Figure out what you want to shoot and then select the best twist in a barrel to shoot that weight ammo. If you want to shoot everything, get the 1/7 twist, you'll just over spin the lighter rounds, some say they are still perfectly accurate like that. Many people are very happy with their 1/9 barrels because they only shoot the cheaper 55gr and sometimes the 62gr stuff. The gouge about the Military selecting the 1/7 twist barrel is that they have to shoot tracers which are much longer bullets for equal weight to non-tracers. |
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Quoted:
Biggest factor to determine the proper twist to stabilize a bullet is the length of the bullet. BUT, since the bullets has to be the same diameter and most are the same basic profile, the length will vary pretty darn close to directly with the length. SO, the gouge you hear is still correct. I believe the gouge is close to this: 1/9 twist, 55-62gr 1/7 twist, 62-85gr The most accurate would be to put the exact amount of spin needed on the bullet, if you can't have that, then more spin is usually better than less spin. I think factors like how balanced or how consistent the bullet is made will affect how well it stabilizes with a certain twist. i.e. those that say that Hornady bullets stabilize in their barrel that supposedly has to little twist to stabilize it. Speed of the bullet as well, so some rounds may have a different muzzle velocity and stabilize better with a certain twist than others. I think, don't really know, the only time to much spin hurts a bullet is far out, near the end of its ballistic arc (long range). Might be why you see folks talk about their 1/7 barrel shooting 55gr just great, because at most plinking ranges, even mid range target shooting, that extra spin isn't hurting. You'll get a dozen different opinions, many will tell you their 1/7 barrels shoot everything perfect, others will tell you they get the most accuracy with the barrel that has a twist closest to the gouge for the weight of bullet they are shooting, other will say the same, but they have found a few exceptions where they can shoot one brand/type of round that is lighter/heavier than the gouge. Like anything with a design, the parameters you select are often a compromise to best cover the conditions you'll use the design in. Figure out what you want to shoot and then select the best twist in a barrel to shoot that weight ammo. If you want to shoot everything, get the 1/7 twist, you'll just over spin the lighter rounds, some say they are still perfectly accurate like that. Many people are very happy with their 1/9 barrels because they only shoot the cheaper 55gr and sometimes the 62gr stuff. The gouge about the Military selecting the 1/7 twist barrel is that they have to shoot tracers which are much longer bullets for equal weight to non-tracers. 'gouge' You keep using this word. I do not think it means what you think it means. I've shot some 50gr and a whole lot of 55gr from my 1/7 barrels. I get the best accuracy with 75gr OTM with groups around 1.5MOA. The 50gr stuff gets me 2 to 2.25MOA. BSW |
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Allow me to restate: The purpose/reason for the Military selecting the 1/7 twist barrel is that they have to shoot tracers, which are 20% longer than non-tracer bullets of near equal weight, in all climates from the Arctic Box to the Sand Box.
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Gouge, at least the way we used in the Marines, was a helpful tip, condensed information or insight. Since it was word of mouth, or condensed down rules of thumb, you always had to be careful that the "gouge" may NOT be applicable.
What do you think "gouge" means? |
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Gouge, at least the way we used in the Marines, was a helpful tip, condensed information or insight. Since it was word of mouth, or condensed down rules of thumb, you always had to be careful that the "gouge" may NOT be applicable. What do you think "gouge" means? Ahhhh! You're using the most obscure, least common, slang meaning. http://en.wikipedia.org/wiki/Gouge BSW |
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From your source:
U.S. Navy Slang
In U.S. Navy jargon, gouge is the essential piece of information; the heart of the matter; or outstanding test-preparation material (such as an old test copy). A person who is tired of hearing all the extraneous information surrounding a problem might exclaim "Just give me the gouge!" Originated at the U.S. Naval Academy and introduced from there into the wider navy, where it sees less frequent usage. That's the way we used it at Annapolis, I saw it more used in the Marines than Navy. That condensing of just the needed information, usually became rules of thumbs, either noted down or passed along as word of mouth. It became more than just the info to help pass a test, it was also notes and tips on procedures, specs, etc. Really don't see how its much different than how I used it. Considering how we can spend pages debating rifle twist, with lots of conflicting references and a hundred people chiming in the total opposite extremes; and considered I've probably fired 1/10th as much as some of the experts on this board, as well never any of the bigger grain ammo, I left it at the info I've seen most people agree on, and called it the gouge. Its been passed to me as gouge. I may be wrong on the upper limit of the 1/7 twist for the heaviest grain bullet you can fire, since I never owned a 1/7 barrel, just fired them active duty. |
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I have read that with a 1/7 twist barrel that shooting lighter 40-50 grain bullets will yeild less accuracy becasue they are over spun. This causes them to yaw up ward as they are first released from the barrel but after lets say 100-150 yards the nose comes back down and the accuracy returns to a little bit closer to what 62gr rounds would achive. I know this wasnt a great description. I know there ahve been other posts on here about it and there have been magazine articles about it too.
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Getting into a Twist about your Twist?!
Anyone that spends any amount of time at the rifle range or hunting lease will inevitably find himself within earshot of two people discussing barrel twist. Twist as discussed here, refers to the rifling in the barrel of modern rifles making a full 360 degree turn in a given length of inches. As an example, a 1x7 Twist means the rifling makes one 360 degree turn for every seven inches of barrel. As it pertains to .223 projectiles, several different twists are currently produced. Not all ammo shoots well in all twist ratios. A barrel with a 1x7 Twist tends to be too tight for most lighter, more commonly fired ammunition. Originally designed for the military's use of SS109 (the official NATO name of 5.56mm, or .223), further military testing concluded other twist ratios are actually superior for this steel core bullet. 1x8 Twist is best suited for 69-80 grain bullets. Our Federal .223 69 Grain BTHP Match Gold Medal is some of the best on the market for this twist ratio. 1x9 and 1x10 twist ratios are sort of the "middle of the road" for .223 projectiles, and these are the most common. We suggest our Hornady TAP 55 Grain. On the lighter side of things, a 1x12 boasts excellent accuracy on standard and lighter projectiles in the 40-52 grain range. Older M16 rifles were manufactured with the 1x12 Twist ratio. Our item number ARR-115 offers a conversion upper for your AR that takes less than a minute to install, and the barrel has a desirable 1x12 twist ratio. If you are buying a varmint rifle chambered in .223, chances are it will sport a 1x12 Twist Ratio. Our Federal Premium .223 Remington 40-Gr NBT is perfect for varminting. Last, we have the 1x14 twist ratio. Probably the least accurate ratio unless you are into bullet tumble as opposed to spin unless you are shooting custom loads. |
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1-12 vs. 1-9 Twist in .223's
by John Barsness NOT ALL THAT LONG AGO, the standard rifling twist in .223 Remington barrels was one turn in 12 inches, but a few years ago new rifles started appearing with 1-9 twists. What does all of this mean to the average shooter? To understand that we have to understand the reasons behind the change. The Nosler Ballistic Tip was one impetus. Prior to the mid-1980's, when the Ballistic Tip was introduced, most shooters saw the .223 as a medium-range varmint cartridge. We considered 300 yards the extreme edge of .223 range; beyond that we needed a .22-250 or .220 Swift. Now, plastic-tipped bullets (and even other "hard-tipped" bullets) had appeared before. But in .224 bullets the Ballistic Tip radically changed the way we thought not just of bullets but varmint cartridges themselves. Before then there were two kinds of expanding varmint bullets: soft-point and hollow-point. The soft-point expanded reliably at long range (or what we thought was long range), while hollow-points were regarded as more accurate. Unfortunately, to make hollow-points expand reliably on small varmints, the "hollow" had to be larger. This cut down drastically on ballistic coefficient. And even the ballistic coefficient of soft-point bullets wasn't all that great. Enter the Ballistic Tip. The plastic tip covered a big hollow-point, so not only raised ballistic coefficient but ensured expansion way out there. Essentially the new bullet combined the expansion of soft-point and accuracy of hollow-point varmint bullets - and increased ballistic coefficient over both. I first shot Ballistic Tips at prairie dogs in the late 1980's. At the time I followed the pretty much standard wisdom of using a .223 for shooting out to 300 yards, especially on calm days, and a larger rifle (in this case a .220 Swift) for shooting beyond 300 yards and in wind. The handload I'd worked up in the .223 used 50-grain Ballistic Tips at around 3400 fps, and accuracy was the best I'd ever gotten from any varmint rifle, well under ½-inch for five shots at 100 yards. During the shoot I found myself using the .223 more and more, and extending the range. Eventually I started shooting prairie dogs at 400 yards, supposedly well beyond the effective range of the .223, because the new bullets not only shot noticeably flatter and very accurately, but expanded violently way out there. During this same period more people started using the .223 for longer-range target shooting, having made the discovery that yes, recoil does enter into good shooting, and ballistic coefficient combined with velocity is what affects long-range accuracy, not just bullet weight. (Actually some shooters knew this, it just took a long time for the average shooter to get over the notion that bullet weight is the main factor in wind drift.) This meant heavier bullets, which in turn meant faster twists. Eventually, too, companies started making "deer" bullets in .224 diameter. I am not going to debate the ethics of shooting deer with ".22's" here. However, it is simple reality that the new deer bullets were longer than typical .224 varmint bullets, whether the 55-grain Trophy Bonded, 60-grain Nosler Partition, or 53-grain Barnes Triple Shock. Eventually, of course, plastic-tipped bullets became the norm for varmint shooting. Almost every company started making them - and plastic-tipped bullets are longer than soft- or hollow-point bullets. Eventually a sort of Catch-22 for .22's evolved. As more shooters started using longer bullets in .223's, more shooters started using faster rifling twists in their .223 barrels - and more people started shooting longer bullets. Eventually it was discovered that another piece of long-time conventional wisdom wasn't true, or at least wasn't as true as it used to be. For centuries rifle shooters had been wary of using bullets that were too short for the twist in their barrels. This was because the bullets then became "over-stabilized," and accuracy went downhill. Even in the 1970's many shooting "authorities" warned that 110-grain bullets didn't shoot all that well in .30-06's, because of the dreaded over-stabilization. This was probably true when those authorities started shooting the .30-06, but by the 1980's most bullets were so well balanced that very short bullets could be shot accurately from twists that were theoretically too fast. One of these well-balanced bullets, of course, was the Nosler Ballistic Tip, which probably also benefited a little from being a little longer than conventional bullets. My wife and I have three .223's in our house, an older, "conventional" Remington 700 with a 1-12 twist heavy barrel, a Bushmaster carbine with a 1-9 twist, and a semi-custom sporter based on the Remington 788 action, with a sporter-weight E.R. Shaw barrel with a 1-9 twist. The 700 is the rifle that shoved all the .22-250's and .220 Swifts we owned out the door (at least for now; Eileen is thinking of another .22-250 for deer hunting). With the advent of laser range-finders and multi-point scope reticles, the .223 proved fully effective for 500 or even 600-yard prairie dog shooting. Why put up with the recoil of a bigger round if it isn't needed? But the Bushmaster and the 788 have also proven very accurate with bullets as light as 40-grain plastic-tips. These two rifles can also, however, shoot very long bullets quite accurately, including 60-grain plastic-tips (now available from both Nosler and Hornady), .224 "deer" bullets, or match hollow-points in the 70-grain range. In fact the 788 will put 68-grain BTHP Hornady's into basically the same hole at 100 yards, and that's a very effective bullet for some varmint shooting, especially way out there when the wind blows. So if you've been nervous about switching to a 1-9 .223, just because you like the way your old .223 shoots those super-fast 40-grain plastic-tips, don't be. A 1-9 will work fine for those too, which is why when the barrel on our old Remington 700 finally goes, the barrel that replaces it will have a 1-9 twist. |
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I should have noted, that I am talking about commercially mass produced ammunition here - M193, M855, LC, Federal, PMC and the like, in both .223 and 5.56. I know there are vast differences in those I noted here.
Thanks to all for the additional input. ETA: the reason I was asking it that I have al older 1:12 twist AR, much newer 1:7 twist Colt barrelled AR, and am contemplating getting in on the Stag group buy, which would be a 1:9 twist barrel. Trying to decide which weight to focus on purchasing for them. I know the 1:12 will nto stabilize the heaver bullets. |
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Originally posed by CAP:
have searched, and don't see exactly what I am looking for. Any reason light weight bullets - 55gr - will not adequeately stabilize in a 1:9 and 1:7 twist barrel? Contrary to some of the nonsense that you may have read on the Internet, quality 55 grain bullets can shoot superbly from fast twist barrels. The 10-shot group pictured below was fired from an AR-15 with a Krieger barrel with a 1:7.7” twist barrel using 55 grain BlitzKings. http://www.box.net/shared/static/gos6vq3szi.jpg “Overspinning” a quality 55 grain bullet from a fast twist barrel does not become an issue unless you have a gyroscopic stability factor greater than 5.0 (which would require something along the lines of a 1:6” twist barrel launching the bullet at over 3500 fps) or unless firing at an angle greater than 85 degrees. /thread |
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In spite of all the numbers, I remember reading that the 1 in 12 twists we had on our early M16 barrels was to "de-stabilize" the bullet, causing the famous deadly "tumble'. O therwise , you're just punching 1/4" holes in things. The idea of a military rifle is to kill humans at medium range. 1 in 12 was perfect for this. The AR platform has expanded and diversified, as has the choice of rifling. Killing "varmints" was never considered in the design.
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In spite of all the numbers, I remember reading that the 1 in 12 twists we had on our early M16 barrels was to "de-stabilize" the bullet, causing the famous deadly "tumble'. Please tell me this is your lame attempt at humor. |
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Sorry Molon, no humor. I live in a lousy neighborhood. My home and family are defended by an AR15 with 1 in 12 twist. " Varmints" probably won't try to break in. To the OP: Build your AR to take on YOUR target. My last take on the subject. Phil US Army 1970 - 1974. In the rice paddies '72 - '73.
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Sorry Molon, no humor. I live in a lousy neighborhood. My home and family are defended by an AR15 with 1 in 12 twist. " Varmints" probably won't try to break in. To the OP: Build your AR to take on YOUR target. My last take on the subject. Phil US Army 1970 - 1974. In the rice paddies '72 - '73. Then you as much as anyone should be arming yourself with facts pertaining to terminal ballistics. Your statement about the reason the 1:12" twist barrel was used on early AR-15s is pure urban legend. |
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Sorry Molon, no humor. I live in a lousy neighborhood. My home and family are defended by an AR15 with 1 in 12 twist. " Varmints" probably won't try to break in. To the OP: Build your AR to take on YOUR target. My last take on the subject. Phil US Army 1970 - 1974. In the rice paddies '72 - '73. Then you as much as anyone should be arming yourself with facts pertaining to terminal ballistics. Your statement about the reason the 1:12" twist barrel was used on early AR-15s is pure urban legend. Just like the AK was designed to shoot the 5.56 in an emergency. That one goes throught the military too. I respect anyone who served a great deal. But that does not make them ballisticians. |
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