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Old 01-13-2010, 18:27   #1
ked
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Why not more 1/8 or 1/7 barrels?

if 55r bullets work OK in a 1/7 barrel, why are most barrels 1/9? seems that a 1/8 would be a GREAT compromise.

thoughts?

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Old 01-13-2010, 20:07   #2
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I don't think most barrels are 1/9. Most of the milspec (top tier, more expensive......whatever you want to call it) barrels are 1/7. I think the BCM SS barrels are 1/8. 1/8 is a good compromise, shoots most things pretty well but Milspec is 1/7 so that's what many of the upper tier manufacturers use. I think 1/7, 1/8, 1/9 are all good as long as its a quality barrel and you are not near the very extremes of bullet weight. Maybe a 1/7 isn't great for a real lightweight varmint bullet, same as the 1/9 may not be good for the 77 grain rounds and bigger. I think all three work fine as long as it's between 55 and 77 grains. Of course all barrels are different, some shoot better than others, some are higher quality etc etc-Norcal911
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Old 01-13-2010, 22:38   #3
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My understanding is that 1/7 is the more recent military designation, and happens to shoot 62-gr. + bullets more accurately for longer distances; this relates to the military more recently designating 62-grain bullet weights as preferable for more applications. I could be way off, I'm sure someone will post a more thorough/accurate explanation if so.

I recently saaw feedback on BCM's 1/8 SS410 barrels and bullet weights - seems users were reporting an odd weight like 68 or 69 grain...something I don't recall having come across. I have some 63-gr soft points, but mostly 62 and 55...been a while since I checked weights in my stock, though. I haven't shot enough through my BCM 1/8 barrel to call any weight better than another.
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Old 01-14-2010, 03:10   #4
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I don't know but I would love to see more 1/8 barrels.
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Old 01-14-2010, 03:24   #5
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Quote:
Originally Posted by furioso2112 View Post
My understanding is that 1/7 is the more recent military designation, and happens to shoot 62-gr. + bullets more accurately for longer distances; this relates to the military more recently designating 62-grain bullet weights as preferable for more applications. I could be way off, I'm sure someone will post a more thorough/accurate explanation if so.

I recently saaw feedback on BCM's 1/8 SS410 barrels and bullet weights - seems users were reporting an odd weight like 68 or 69 grain...something I don't recall having come across. I have some 63-gr soft points, but mostly 62 and 55...been a while since I checked weights in my stock, though. I haven't shot enough through my BCM 1/8 barrel to call any weight better than another.
The 1/7 twist was developed to stablaize the military tracer round which is very very long. 1/7 is actually more than is needed for heavy .223 bullets even as heavy as 90 grains. The 1/8 twist is about ideal. The 1/9 is ok but sometimes will and sometimes won't stabilize the heavy bullets. The heavy bullets are the best performers in the 5.56 in terms of long range accuracy and terminal performance. (ie stopping power)
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Old 01-14-2010, 14:30   #6
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Quote:
Originally Posted by Alaskapopo View Post
The 1/7 twist was developed to stablaize the military tracer round which is very very long. 1/7 is actually more than is needed for heavy .223 bullets even as heavy as 90 grains. The 1/8 twist is about ideal. The 1/9 is ok but sometimes will and sometimes won't stabilize the heavy bullets. The heavy bullets are the best performers in the 5.56 in terms of long range accuracy and terminal performance. (ie stopping power)


I believe we could do away 1/9 and 1/7 twist barrels completely and just have one twist rate for most production rifles.....the 1/8.

Varminters could always use a 1/12 for the super light stuff. But the 1/8 would handle the biggest variety of rounds, 50 grainers to the stuff in the 80's that you have to single load.

I actually talked to a custom barrel maker and his idea is that a 1/8.5 twist is "ideal" for an AR. I'd agree with that and wish I could get a chrome lined 1/8 barrel.
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Old 01-14-2010, 15:01   #7
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BCM makes a 410 Stainless barrel in 1/8. That's even better than chrome-lined, yeah?
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Old 01-14-2010, 15:27   #8
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Quote:
Originally Posted by furioso2112 View Post
BCM makes a 410 Stainless barrel in 1/8. That's even better than chrome-lined, yeah?
Not a bad choice.
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Old 01-14-2010, 16:55   #9
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Quote:
Originally Posted by furioso2112 View Post
BCM makes a 410 Stainless barrel in 1/8. That's even better than chrome-lined, yeah?
Its a good barrel but not better than chrome lined. Well let me rephrase that. Not better from the standpoint of service life, ease of cleaning and corrosian resistance. Chrome is better than stainness in those areas. Stainless is generally more accurate because chrome can not be plated 100% consistently so the barrels generally are not quite as accurate as stainless.
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Old 01-14-2010, 17:12   #10
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I'd love BCM to offer some "standard" 1/8 barrels.
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Old 01-14-2010, 18:25   #11
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1:8 is all we offer, it works well with everything except the 90gr VLDs.
Most use 1:7 because they are military spec and every barrel maker has them so they are cheap, they don't have to buy a special button and wait for the 7s to be made they just call up and ask for a few hundred from the stack.
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Old 01-14-2010, 18:35   #12
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I'd love BCM to offer some "standard" 1/8 barrels.
ME TOO!!
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