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Posted: 5/23/2012 11:49:28 AM EDT
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SO I am building my first AR-15 and have the lower completed (for now) and I am looking at doing the upper. What are the differences with the barrel twists? I understand that the 1:9 will twist more than a 1:7 and that 1:7 means the bullet turns 1 revolution for every 7 inchs. What I'd like to know is what does it mean for accuratcy? I would like a 16-18 inch free float barrel.
Thank you. |
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1:7 means it revolves 1 time in 7 inches.
all twist can be equally accurate it is the type of bullet you intend to use that is a factor a 1:9 will not stabilize heavier/longer bullets but works great with the standard 55gr a 1:7 will be better suited for your heavier long range bullets |
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Quoted:
1:7 means it revolves 1 time in 7 inches. all twist can be equally accurate it is the type of bullet you intend to use that is a factor a 1:9 will not stabilize heavier/longer bullets but works great with the standard 55gr a 1:7 will be better suited for your heavier long range bullets This Accuracy will only come into play on twist when longer heavier bullets are used but the 55gr will preform nearly the same out of each. I personally own 1/8 and 1/7 rifles but no 1/9 (not because they are bad just how the cards have fallen.) |
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1:12 is really only good for varmint bullets and right on the edge with 55s
1:9 is generally good up to about 70gr with lead core bullets, though some report it working with 77SMKs 1:8 will get you to around 80gr for sure sometimes heavier 1:7 is only needed for bullets so long you have to single load them or drastically sacrafice powder capacity. Technically length matters not weight, so if your plans include unleaded bullets you want a faster twist (smaller number) Generally its better to spin a bullet faster than neccesary than not fast enough. For most people the only real downside to overspinning a bullet is with very light varmint bullets moving very fast, they can disinegrate under the right circumstances. |
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Quoted:
Quoted:
1:7 means it revolves 1 time in 7 inches. all twist can be equally accurate it is the type of bullet you intend to use that is a factor a 1:9 will not stabilize heavier/longer bullets but works great with the standard 55gr a 1:7 will be better suited for your heavier long range bullets This Accuracy will only come into play on twist when longer heavier bullets are used but the 55gr will preform nearly the same out of each. I personally own 1/8 and 1/7 rifles but no 1/9 (not because they are bad just how the cards have fallen.) Good intel here. 
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Quoted:
1:12 is really only good for varmint bullets and right on the edge with 55s 1:9 is generally good up to about 70gr with lead core bullets, though some report it working with 77SMKs 1:8 will get you to around 80gr for sure sometimes heavier 1:7 is only needed for bullets so long you have to single load them or drastically sacrafice powder capacity. Technically length matters not weight, so if your plans include unleaded bullets you want a faster twist (smaller number) Generally its better to spin a bullet faster than neccesary than not fast enough. For most people the only real downside to overspinning a bullet is with very light varmint bullets moving very fast, they can disinegrate under the right circumstances.  Not to be rude, but your appraisal of 1:7 twist seems quite off.
OP, there is a really good FAQ tacked at the top of the AR discussions board that answers this question very well. AFAIK 1:9 will handle 45-70grains depending on bullet length. 1:7 and 1:8 will handle55-77 or 80 grains also depending on bullet length ETA: 1:7 is the most common twist rate and with availability of parts as of late that may factor in to your decision depending on how soon you want your build done |
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Quoted:
Quoted:
1:12 is really only good for varmint bullets and right on the edge with 55s 1:9 is generally good up to about 70gr with lead core bullets, though some report it working with 77SMKs 1:8 will get you to around 80gr for sure sometimes heavier 1:7 is only needed for bullets so long you have to single load them or drastically sacrafice powder capacity. Technically length matters not weight, so if your plans include unleaded bullets you want a faster twist (smaller number) Generally its better to spin a bullet faster than neccesary than not fast enough. For most people the only real downside to overspinning a bullet is with very light varmint bullets moving very fast, they can disinegrate under the right circumstances. Not to be rude, but your appraisal of 1:7 twist seems quite off.
OP, there is a really good FAQ tacked at the top of the AR discussions board that answers this question very well. AFAIK 1:9 will handle 45-70grains depending on bullet length. 1:7 and 1:8 will handle55-77 or 80 grains also depending on bullet length ETA: 1:7 is the most common twist rate and with availability of parts as of late that may factor in to your decision depending on how soon you want your build done What I am finding is that the 1:8 and 1:9 are more common here where I live for some reason andI am not finding alot of 1:7 at all. Thanks for all the information! |
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Quoted:
Quoted:
1:12 is really only good for varmint bullets and right on the edge with 55s 1:9 is generally good up to about 70gr with lead core bullets, though some report it working with 77SMKs 1:8 will get you to around 80gr for sure sometimes heavier 1:7 is only needed for bullets so long you have to single load them or drastically sacrafice powder capacity. Technically length matters not weight, so if your plans include unleaded bullets you want a faster twist (smaller number) Generally its better to spin a bullet faster than neccesary than not fast enough. For most people the only real downside to overspinning a bullet is with very light varmint bullets moving very fast, they can disinegrate under the right circumstances. Not to be rude, but your appraisal of 1:7 twist seems quite off.
OP, there is a really good FAQ tacked at the top of the AR discussions board that answers this question very well. AFAIK 1:9 will handle 45-70grains depending on bullet length. 1:7 and 1:8 will handle55-77 or 80 grains also depending on bullet length ETA: 1:7 is the most common twist rate and with availability of parts as of late that may factor in to your decision depending on how soon you want your build done Not rude, just a baseless claim. Guess I didn't emphasize NEEDED enough, I didn't say it wouldn't work for lighter/shorter bullets, just that it was not neccesary for most people who mag feed their ARs, if you're over 80gr you're single loading or sacrificing powder capacity. OP 1:8 or 1:7 would probably be best for a general purpose AR as it gives the option of the heavies which most prefer for long range. |
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