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Posted: 8/8/2014 8:08:36 AM EDT
| need to know what rifling is best with what grain bullet 1-7 vs 1-9 vs... |
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Barrel length is a key factor in this question because it affects the velocity of the bullet. Here is some general info on twist rates, but understand that things can get kind of convoluted when factoring different variables into the equation (bullet type, handloads vs factory, weight of projectile, etc)
I'm sure I will be critiqued on the specifics of the 1-9, 1-8 and 1-7, but understand there are ranges of grains to use with different twists and many of the ranges overlap each other, but then it is all affected by barrel length. 1-10 twist: In general: good for shooting 55 grain, when you pack in much more, the twist rate isn't able to fully stabilize the bullet causing stability problems. I think technically you can shoot up to ~65 grains with this rate. I wouldn't recommend this rate because it is somewhat limited if you are sport shooting, i.e. it's not as versatile as a quicker twist barrel. 1-9 twist: Good rate for the heavier bullets and bigger loads. 69 grains is good for this rate, wouldn't go much higher unless you are using a longer barrel and thus have higher velocities. This twist will also shoot 55-grains just fine. I have a 1-9 twist 16" and I shoot 55's out of it without accuracy problems. This twist is a good overall rate for carbines (probably the 2nd most versatile) 1-8 twist: Most versatile for the general AR platform if you are staying around a 16" barrel. This twist is pretty versatile with velocities as well as grains which means you have more room to adjust your barrel length with this twist as opposed to other twist rates. Shoot up to 75? grains with this. You can probably shoot even heavier loads but I have not tried it. Shoot down to 55 grains just fine (as long as you don't have a 24" barrel) 1-7 twist: Military uses this rate for the m4 platform. Good twist rate for shorter barrels. Shoots up to 90 grains without stability problems. This twist rate is where you can get yourself into trouble with length vs grains. In general shooting a longer barrel (maybe...18"+) with less grains (~55 grains) in this twist rate will yield stability problems. However, if you shot the same grains (55) and same twist in a 11.5" barrel, it would perform excellently. Hope this helps. EDIT I found this 10 minutes after I posted. But, as you know by now, the picture below changes when you get away from 16" barrels! http://i1347.photobucket.com/albums/p704/nod3ns/Twist_VS_Grain_zps8b69da51.jpg |
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I stuck it out and waited (sometimes impatiently) for a 1:8 twist barrel for what I could afford. I originally planned to go with a mid gas system 18" 1:8 twist barrel. Then I got a deal I couldn't pass up on a 7" free float handguard with a rail height gas block so that changed my barrel choice to a carbine gas system. Got a great deal from Anderson Mfg when they had their Fathers Day offer with a 15% discount and free shipping so I got their 1:8 twist 16" barrel for $99 and some coins. I could not be happier with it. The installation of it went perfectly and it was the last part I needed to finish the rifle I had been building for 1½ years.
So, get yourself a 1:8 twist barrel if you can. It is the best overall twist rate that stabilizes the widest variety of bullet weights. |
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Quoted:
1-8 with polygonal rifling will be the more versatile and accurate... AlabamaPaul, are you a fan of polygonal rifling and why? I have found many barrels that suit me but dismissed them because they were polygonal. I believe I asked this question before, I'm not sure, so if I did please bear with me. |
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Quoted:
Barrel length is a key factor in this question because it affects the velocity of the bullet. Here is some general info on twist rates, but understand that things can get kind of convoluted when factoring different variables into the equation (bullet type, handloads vs factory, weight of projectile, etc) I'm sure I will be critiqued on the specifics of the 1-9, 1-8 and 1-7, but understand there are ranges of grains to use with different twists and many of the ranges overlap each other, but then it is all affected by barrel length. 1-10 twist: In general: good for shooting 55 grain, when you pack in much more, the twist rate isn't able to fully stabilize the bullet causing stability problems. I think technically you can shoot up to ~65 grains with this rate. I wouldn't recommend this rate because it is somewhat limited if you are sport shooting, i.e. it's not as versatile as a quicker twist barrel. 1-9 twist: Good rate for the heavier bullets and bigger loads. 69 grains is good for this rate, wouldn't go much higher unless you are using a longer barrel and thus have higher velocities. This twist will also shoot 55-grains just fine. I have a 1-9 twist 16" and I shoot 55's out of it without accuracy problems. This twist is a good overall rate for carbines (probably the 2nd most versatile) 1-8 twist: Most versatile for the general AR platform if you are staying around a 16" barrel. This twist is pretty versatile with velocities as well as grains which means you have more room to adjust your barrel length with this twist as opposed to other twist rates. Shoot up to 75? grains with this. You can probably shoot even heavier loads but I have not tried it. Shoot down to 55 grains just fine (as long as you don't have a 24" barrel) 1-7 twist: Military uses this rate for the m4 platform. Good twist rate for shorter barrels. Shoots up to 90 grains without stability problems. This twist rate is where you can get yourself into trouble with length vs grains. In general shooting a longer barrel (maybe...18"+) with less grains (~55 grains) in this twist rate will yield stability problems. However, if you shot the same grains (55) and same twist in a 11.5" barrel, it would perform excellently. Hope this helps. EDIT I found this 10 minutes after I posted. But, as you know by now, the picture below changes when you get away from 16" barrels! http://i1347.photobucket.com/albums/p704/nod3ns/Twist_VS_Grain_zps8b69da51.jpg For years I have known about the twist rates but to see it on your graph makes it so clear, good job ANTAR3S!!! Stephen |
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Quoted: 1-8 with polygonal rifling will be the more versatile and accurate... |
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1:8 gives you the best coverage for most common bullet weights. I think the chart provided, is a bit narrow on ranges because I get better than MOA from my 1:8 barrel.
Poly rifling... distorts the bullet less than land-and-groove types, and those that make them are generally well regarded because not many do. I use the Rainier Select Medcon 18" with the 1:8. Black Hole makes them for Rainier. I can attest to the accuracy as well as the easiness to clean. Because there are no sharp edges (a la standard rifling) there really isn't a place for copper or fouling to deposit. |
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