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Posted: 3/31/2006 10:13:52 AM EDT
[#1]
Uh..
M855.. Or just plain 62gr lead? Reason I ask is, the M855 bullet wieghs 62gr but uses a steel penetrator.. and steel is not as dense as lead, so its a long bullet... If your shooting M855.. 1/7 is the way to go.. military found that to be the optimal twist rate for it. |
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Posted: 3/31/2006 10:15:21 AM EDT
[#2]
take a look at the Ammo Oracle
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Posted: 3/31/2006 10:16:25 AM EDT
[#3]
I'll make it easy for you...
1:9 Don't have a wet dream and beg someone to create an oddball 1:9.5 twist or whatever, that's flat out stupid. Look at it like this: 1:9 will do 55-69 grains. 1:7 will do 62-80 grains. There's some overlapping but that's the general idea. As you can see both twist rates will handle some stuff the other can. You could also custom build a 1:8 I suppose.... |
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Posted: 3/31/2006 10:19:13 AM EDT
[#4]
Not quite. M855 -> 1/9 M856 -> 1/7 |
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Posted: 3/31/2006 10:21:04 AM EDT
[#5]
Thank you Jonathan… I am thinking of not going with the M855 as other bullets are more accurate, as I understand.
So the 1 in 7 twist was designed for the M855 that makes a lot of sense. And I imagine for non-M855’s that is still probably a very close ideal twist. |
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Posted: 3/31/2006 10:21:41 AM EDT
[#6]
uh.....no. Check the link above....here's a quote: "Rounds in flight spin for stability because of the rifling on the inside of the barrel. Depending on how much they spin, they are more or less stable in their flight and therefore more or less accurate. The earliest AR15s from the early 1960s had a twist rate of 1 complete twist every 14", or 1:14. This was increased to a twist rate of 1 turn in 12" for the M16, XM16E1, M16A1, and later rifles and carbines. The current M16A2s and up and the M4 carbines have a much faster twist rate, 1 turn in 7". The reason for the 1:7 twist is mainly to stabilize the M856 tracer bullet, which is much longer than other bullets. You will recall from above that the M856 was designed to provide 800 meters of trace out of the SAW." |
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Posted: 3/31/2006 10:28:13 AM EDT
[#7]
Okay I was wrong, but instead of insulting me, perhaps it is better to be nice about it? And some folks really wonder why ARFCOM has a huge rep on the net for being a place being very unfriendly.
 Nice edit there Hokie |
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Posted: 3/31/2006 10:34:21 AM EDT
[#8]
Another quote:
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Posted: 3/31/2006 10:37:01 AM EDT
[#9]
I made the edit so you don't run away all butt hurt. Still.......you should homework before you post in a technical thread and you can avoid big mean bullies like me correcting you. sorry to ruffle your feathers up there  Don't make me fly to WA and give you a warm & gay ARFCOM hug & kiss. 
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Posted: 3/31/2006 10:49:16 AM EDT
[#10]
Hey now, I am not TRG!   Sorry if I took it the wrong way.. I honestly LIKE being told when I am wrong about a fact, means I can correct my own personal error.. I still prefer 1/7 twist though, but I actually do shoot 75gr and 77gr bullets often enough(and I use them for defense loads as well). Personal preference.. but yeah |
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Posted: 3/31/2006 10:53:03 AM EDT
[#11]
i would think 1x8 would be the happy medium is 62gr. is all you are planning to shoot.
but in my exp. the 1x9 would fair much better if you plan on shooting 62 or less |
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Posted: 3/31/2006 10:57:33 AM EDT
[#12]
  For what it's worth I also choose 1:7 but also have a 1:9...either will run 62 grain just fine. If 62 was all our hero is gonna shoot, then I think a 1:9 would be best for his application. |
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Posted: 3/31/2006 8:12:23 PM EDT
[#13]
I have a 1 in 8 on my Oly PCR-1, that way I have a wider range. I mostly shoot Sierra 89grs BTHP but sometimes will shoot 55grs FMJs and Sierra 80grs HPBT and all shoot sub 1" at 100 yards. It works well for me but the 1 in 9 should also work quite well.
Jim |
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Posted: 4/1/2006 2:38:51 AM EDT
[#14]
62 gr works well in my 1:9
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Posted: 4/5/2006 9:57:03 AM EDT
[#15]
I have shoot 55's from my 1/7 it works fine I have shoot 45 gr -77 in my 1-9 never had a problem. I shot 62's out of 1/12 it was fine to .
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Posted: 4/5/2006 12:43:15 PM EDT
[#16]
This has always been the rule but some Master Lemming got the ARFCOM community chanting 1:7 1:7 1:7. There is no perfect twist that will handle all of it perfectly. Figure out what you shoot most and pick the twist rate. Or do as most do, buy both. 
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Posted: 4/5/2006 1:04:53 PM EDT
[#17]
it's the only real solution here
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Posted: 4/11/2006 10:34:29 PM EDT
[#18]
I believe the military's decision for 1/7 was a compromise between the optimun 1/6 twist for tracers and optimum 1/8 twist for M855. I myself prefer 1/9 and use it exclusively for all my builds.
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Posted: 4/12/2006 10:15:19 AM EDT
[#19]
Wow, found this web site and you can compute the exact twist....
stevespages.com/page8e.htm Now thats the ticket 
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