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View Full Version : 1/7 twist or 1/9 twist?


Rockhound
10-16-2009, 8:19 AM
Does anyone have opinions on this? I am looking at either a Stag upper with 1/9 twist, CMMG with 1/7, or Yankee Hill with 1/7 twist.

I will be goning with a 16" barrel and shooting mostly 55grn 62 grn bulk .223 ammo.

SCMA-1
10-16-2009, 8:27 AM
Does anyone have opinions on this? I am looking at either a Stag upper with 1/9 twist, CMMG with 1/7, or Yankee Hill with 1/7 twist.

That depends on what type of ammunition you plan on shooting the most of. If most of your shooting will be done with cartridges loaded with very long bullets such as M855/M856 or handloaded 70-80gr match bullets, then 1x7 may be better for you. If most of your shooting involves M193 ball (55gr FMJBT) and perhaps some M855/SS109 (62gr) and occasionally some 69gr SMK match loads, 1x9 would be more suitable.

Virtually all my barrels (with the exception of a few 1x12) are 1x9 because I shoot mostly bulk M193 and some match loads up to 70gr.

pacrimguru
10-16-2009, 8:32 AM
Does anyone have opinions on this? I am looking at either a Stag upper with 1/9 twist, CMMG with 1/7, or Yankee Hill with 1/7 twist.

it depends on what kind of shooting you are planning to do too. length of barrel comes into play as well. but honestly for the most part, i think for most casual shooters it really doesn't matter too much. i have had both the stag 1/9 and cmmg 1/7 and they both shoot great.

THT
10-16-2009, 9:00 AM
Unless you're going to be using this for varminting or other activities involving sending lightly-jacketed, light bullets, go with the 1:7 twist barrel as it will allow your rifle to stabilize heavier bullets while still being able to also shoot 55gr milsurp.

BHPFan
10-16-2009, 9:11 AM
Does anyone have opinions on this? I am looking at either a Stag upper with 1/9 twist, CMMG with 1/7, or Yankee Hill with 1/7 twist.


I feel 1/9 is a little more versatile though both can do the job. 1/7 is better for heavier loads (69 grains and above)

BHPFan
10-16-2009, 9:12 AM
Unless you're going to be using this for varminting or other activities involving sending lightly-jacketed, light bullets, go with the 1:7 twist barrel as it will allow your rifle to stabilize heavier bullets while still being able to also shoot 55gr milsurp.

I thought 1/9 is better for the lighter 55gr loads (though 1/7 can still shoot them) while 1/7 is better for the heavier loads.

Rockhound
10-16-2009, 9:24 AM
I will be goning with a 16" barrel and shooting mostly 55grn 62 grn bulk .223 ammo.

THT
10-16-2009, 9:25 AM
I will be goning with a 16" barrel and shooting mostly 55grn 62 grn bulk .223 ammo.

For your purposes, either will work however the faster twist will give you the flexibility to shoot heavier bullets should you choose to.

Darklyte27
10-16-2009, 9:29 AM
for the love of whoever your god is or isnt! do a search! this is the 230498320498th time this question gets asked.. and its not like you are a noob either, you been with calguns for almost a year!

BHPFan
10-16-2009, 9:53 AM
For your purposes, either will work however the faster twist will give you the flexibility to shoot heavier bullets should you choose to.

That's good to know.

That will save me the trouble of spending $$ to buy a 1/9 barrel and rebarrel my AR from 1/7 to 1/9 so I can shoot the bunch of M193 ammo that I got.

coop44
10-16-2009, 10:00 AM
1/7 or 1/9 will work well for the heavies, but if you ever want to shoot 45-50 grain varmit bullets, 1/9. at 30k rpm the 1/7 45 grain bullets may come apart. GO to the shilen web site they have some good info and a chart covering what twist will be suitable for what bullet

coop44
10-16-2009, 10:11 AM
for the love of whoever your god is or isnt! do a search! this is the 230498320498th time this question gets asked.. and its not like you are a noob either, you been with calguns for almost a year!


Christ, yes.
Here I did the search for you.

http://www.shilen.com/calibersAndTwists.html

missiontrails
10-16-2009, 10:19 AM
I say 1/7, because that is usually paired with better barrel steel.

Capt Jack
10-16-2009, 10:26 AM
Yup, I'd also agree on 1/7. I was in the same boat when choosing my upper and am glad I went with the CMMG.

It shoots 55 gr fmj just fine!

Rockhound
10-16-2009, 10:58 AM
Thanks, all the info helped. And thanks of the link. I'll do more searching on future questions.

1988
10-16-2009, 6:41 PM
I will be goning with a 16" barrel and shooting mostly 55grn 62 grn bulk .223 ammo.

1/9 twist.

1/7 twist is a must if you consider to use 75-77gr rounds. I found my 1/9 uppers not handling the 75-77gr ammo that well.

God Bless The Mauser
10-16-2009, 6:51 PM
[QUOTE=Darklyte27;3222621]for the love of whoever your god is or isnt!
QUOTE]

That was a good laugh.

johnrunner89
10-16-2009, 7:02 PM
I say 1/9...but thats me. I dont shoot anything heavier than 70grains

3GunFunShooter
10-16-2009, 7:13 PM
Get a 1/8 shoots all the ammo great. 55gr to 77gr. JP offers it for their rifles.

Jonathan Doe
10-16-2009, 7:50 PM
Does anyone have opinions on this? I am looking at either a Stag upper with 1/9 twist, CMMG with 1/7, or Yankee Hill with 1/7 twist.

I will be goning with a 16" barrel and shooting mostly 55grn 62 grn bulk .223 ammo.

If this is the case, 1/9 will do a good job. Barrel twist is not just related to the bullet weight, but more importantly, the length of the bearing surface of the bullet.

Greg-Dawg
10-16-2009, 7:58 PM
1/7 because my Bravo Company M4 16" says so.

Noobert
10-16-2009, 8:45 PM
I think 1/9, since 223 aren't meant to go heavy anyways, so 1/7 is more restrictive

ponderosa
10-16-2009, 11:36 PM
at least there is a consensus ;) haha. now i'm confused sounds like both are best.

actually 1x9 has more 'votes' so far...

1x9: 7 votes
1x7: 4 votes
1x8: 1 vote

randy
10-17-2009, 1:23 AM
I'm a 1 in 8 vote. Big range in bullets you might miss the extreme ends of the scale though.

Richie Caketown
10-17-2009, 1:31 AM
1x7 here

k_corj
10-17-2009, 1:34 AM
I think 1/9, since 223 aren't meant to go heavy anyways, so 1/7 is more restrictive

Riiight.

Heavy grain bullets are ballistically superior to the lighter loads in every way.

You are restricting yourself more by not being able to use some of the best .223 ammo out there by going with a 1/9

Unless you are going to shoot really lightweight varmit bullets like the 36gr varmint grenade then 1/7 is better. Even then you can still shoot 45gr Vmaxs from a 1/7 if you want to blow up critters.

Raptor1Ronin
10-17-2009, 8:49 AM
Love my 1/9 here.

Noobert
10-17-2009, 11:27 AM
Riiight.

Heavy grain bullets are ballistically superior to the lighter loads in every way.

You are restricting yourself more by not being able to use some of the best .223 ammo out there by going with a 1/9

Unless you are going to shoot really lightweight varmit bullets like the 36gr varmint grenade then 1/7 is better. Even then you can still shoot 45gr Vmaxs from a 1/7 if you want to blow up critters.

Well, if you want a good heavy round, why not get a 308? shooting a heavy .223 is like diving a souped up honda instead of a corvette

akjunkie
10-17-2009, 6:38 PM
For what it's worth..

1:9 twist for me

http://ammo.ar15.com/ammo/project/perf_whattwist.html

"The majority of shooters, though, typically shoot bullets of 50 to 69 grains in weight (note that the 62gr SS-109/M855 bullet is as long as a 71 grain lead core bullet) and should select 1:9 twist barrels. At typical .223 velocities, a 1:9 twist will stabilize bullet lengths equivalent to lead-core bullets of 40 to 73 grains in weight."

Loner
10-17-2009, 7:33 PM
Get both.

1988
10-17-2009, 9:31 PM
Get a 1/8 shoots all the ammo great. 55gr to 77gr. JP offers it for their rifles.

+1

It's a good compromise. However, I found only a handful number of makers have them in match barrels.

SanSacto
10-17-2009, 9:40 PM
1/7 because my Bravo Company M4 16" says so.

I think you are right, because my LMT tells me 1/7 also! :cool:

Josh3239
10-17-2009, 11:28 PM
I use 1:7. Generally 1:7 will handle 55gr to 77gr, though the size of the bullet makes more of a different than weight.

snupples
10-18-2009, 12:48 PM
1/7

Because it is more versatile considering that the 5.56/.223 commonly used in ARs starts at 55gr and up, which is well within the 1/7 range.

And the trend is moving toward heavier ammo (like 75gr TAP).

Rockhound
10-20-2009, 7:27 AM
I read em all and I'm going with.......................1/7. I like Loners idea of both, maybe on the next build.

Thanks

technique
10-20-2009, 7:34 AM
1/7 is what I like..to me there is no need to shoot anything lighter than a 55gr.

1/7 can shoot 55gr on up to 75-79gr. so it has a wide range from average ammo you would see surplus for, and heavier specialty loads for home defense or longer range stability.

1/9 is alright, you can shoot the lighter loads but just like with the heavy loads you are getting into novelty stuff so its not necessarily cheaper to load or buy projectile wise(YMMV)..