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1:8 or 1:9...

 
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  #1  
Old 11-03-2012, 07:24 PM
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1:8 or 1:9...

1:8 or 1:9 twist in a 5.56 AR... if you need more info i can provide it i just dont know much about this stuff so thats why im asking hopeing to learn... thanks
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Old 11-03-2012, 07:57 PM
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Re: 1:8 or 1:9...

I personally like the 1:8... it allows me to shoot the larger grain bullets and will still shoot 55 grainers as well. If you plan on shooting any kind of distance you will really want the faster twist rate so you can stabilize them. I shot a shoot last weekend and made the mistake of shooting 55 grainers. They worked very well out to about 550 when there was little to no wind. Next year I will be shooting the heavier bullets.

Hope that helps a little

Ryan
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  #3  
Old 11-05-2012, 09:48 AM
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Re: 1:8 or 1:9...

Wizbang,

The 1x9"s are really something of a hold-over, whose time has come and gone, at least in my opinion. The 1x9"s are ideal for 68-69 grain bullets, but won't handle any of the later developments like the 75s, 77s or 80s. The 1x7" or 1x8" will, and will also shoot the 69s just as well. A bit of extra spin will almost never cause problems, while insufficient spin is ALWAYS a problem. Go with the faster twists, and forget about the 1x9".
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Old 11-05-2012, 10:30 AM
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Re: 1:8 or 1:9...

Quote:
Originally Posted by Kevin Thomas View Post
Wizbang,

The 1x9"s are really something of a hold-over, whose time has come and gone, at least in my opinion. The 1x9"s are ideal for 68-69 grain bullets, but won't handle any of the later developments like the 75s, 77s or 80s. The 1x7" or 1x8" will, and will also shoot the 69s just as well. A bit of extra spin will almost never cause problems, while insufficient spin is ALWAYS a problem. Go with the faster twists, and forget about the 1x9".
Do this its good advice, I have a 1-7 in all of mine but the mil moved to a 1-8 for all its 18" barreled SPRs everything else is a 1-7. I think the 1-8 choice for the spr had to do with the bullets they chose to use. The 77g SMK (77g Nosler for a short time) etc. The magority of the guys have the 1-7 and are using bullets ranging from 62 to 77g.
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Old 11-06-2012, 05:26 AM
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Re: 1:8 or 1:9...

Unfortunately, all of my AR's are 1:9, but they do handle the 69 gr SMK's very well. Berger has a 73 grain target that is supposed to be 1:9 friendly. Beyond those weights you start to run into problems with the magazine length.
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Old 11-06-2012, 09:56 AM
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Re: 1:8 or 1:9...

The problems beyond these with the 1x9" remains one of twist, not mag length. So long as it's got a 7 caliber ogive or less, it will work as "mag length" at 2.260" The problem with the 75s-77s is that they need the faster 1x8" twist. I routinely use 77s for my Across the Course shooting, switching to 80s or 82s for the 600 yard stages, Since the 600 yard stage is designated as "slow fire", the rounds must be single loaded; the rules don't allow them to be fed from the mag. As a result, the heavier bullets intended for these strings generally use a 12-15 caliber ogive, and are usually seated out to around 2.450" or more. Here, the inability to function trhough a mag isn't a problem at all, and is what allowed the more extreme designs to come to be.
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Old 11-06-2012, 10:28 AM
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Re: 1:8 or 1:9...

I like the 1-7 in my 16" MRP a 70g ttsx fly's to the same point of impact as a 55g M885 at 100M. I only see myself going 1-8 or 1-9 if I was building a rifle for dog towns and wanted the real light explosive screamers. For what I do the 1-7 is perfect it allows me to use the 55g bullets for my inside 200m training and the heavy 70g bullet for the crop damage deer and what ever else in the summer.
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