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fallenknight308
01-30-2009, 1:23 PM
1/7 or 1/9 Twist?
I will need to use a wider variety of ammo than some, (cheap, surplus ect)
Is the 1/9 better for this?
I saw these two, but they are both 1/7:
http://www.bravocompanyusa.com/ProductDetails.asp?ProductCode=BCM%2DURG%2DMID%2D1 6
http://cmmginc.secure-mall.com/shop/?shop=1&cat=27&
This RRA I saw is 1/9 though:
http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=266

fusionstar
01-30-2009, 1:42 PM
surplus.. like 55 grain? The both shoot 55 grain fine. The added bonus of 1:7 is you can go up to the 77 gr match kings with no no problem. In the 1:9 it will start keyholeing. But the 1:7 cant shoot very light stuff where as the 1:9 might.

tommyid1
01-30-2009, 1:50 PM
as said above it depends entirely on what you will be shooting Bullets wise. if you are shooting surpluss or the cheap stuff stick with the 1/9 as most are 55gr bullets that 1/9 stabilizes fine

fallenknight308
01-30-2009, 1:52 PM
surplus.. like 55 grain? The both shoot 55 grain fine. The added bonus of 1:7 is you can go up to the 77 gr match kings with no no problem. In the 1:9 it will start keyholeing. But the 1:7 cant shoot very light stuff where as the 1:9 might.
This will be a tactical/zombie defense rifle, not much of a sniper.
But I would like to get out to 600yd with it. And I want shoot that green tipped stuff too (steel core I think) :cool:

postal16
01-30-2009, 1:58 PM
i have 1:7 on my Service Grade Match and Varmit rifles so I can go up to 80 grains, though I mostly shoot 69 gr HPBT for up to 300 yards. They both drive tacks

1:9 on my Carbine (since I will not be shooting anything greater than 69 grs)

cmace22
01-30-2009, 2:06 PM
1/8...... best of both worlds

fallenknight308
01-30-2009, 2:08 PM
The more I read about it, the more I'm leaning towards 1/7:)
Sig357, please help me to make that "Newbie tips" better, what are you still confused in terms of 1/7 and 1/9?

I quoted this thread (http://www.calguns.net/calgunforum/showthread.php?t=26518) in the "tips" posting, and it does explain the capability of both 1/7 and 1/9.

Theoretically,
1x7 shoots anything from 50gr - 77gr and to even heavier ones like 80gr and 90gr(but 80/90 are not magazineable)
1x9 shoots anything from 40gr - 69gr

So, for the most popular XM193, 55gr or XM855, 62gr.... BOTH will shoot fine.... the DIFFERENCES would be the low and high end.....

varmint specific bullets 40-50gr will be served by 1x9 and not 1x7... (by the way, you can shoot varmint with 50gr or 55gr bullets :D)

recently developed(more like adopted), military performance rounds, 75-77gr will be served by 1x7 and not 1x9... ie. these longer range, premium rounds, cannot be stablized with a 1x9 barrel...

and the military had switched over to 1x7 barrels for a long time now.... and basically those heavier bullets (75-77gr), are used to extend the performance of the M16 platform....

so, imho, 1x7 is the way to go

hope this helps.

fusionstar
01-30-2009, 2:20 PM
The green tip ss109 or m855 is 62 grain bullet with a steel penetrator, it Will stabilize in both 1:7 and 1:9. Both twist rates are equally accurate so it narrows down to bullet choice. MOST surplus rounds are 55 and 62 grainers. If you wish to go out to 600 yards with consistency and repeatability. the 1:7 with a 20" or 24" barrel will get you there easily with the heavier Bullets 69 and above. The 16" barrels can get you there but the drop in velocity is a real factor at those distances. You lose anywhere from 50-100 FPS per inch of barrel. The longer it takes a bullet to get to its target, the longer gravity, wind will effect it. This is where heavy bullets come into play. They dont get effected by wind as much.

Expect minute of 2 man accuracy at 600 yards out of a run of the mill barrel and a nice scope setup with surplus M855.

fallenknight308
01-30-2009, 2:30 PM
The green tip ss109 or m855 is 62 grain bullet with a steel penetrator, it Will stabilize in both 1:7 and 1:9. Both twist rates are equally accurate so it narrows down to bullet choice. MOST surplus rounds are 55 and 62 grainers. If you wish to go out to 600 yards with consistency and repeatability. the 1:7 with a 20" or 24" barrel will get you there easily with the heavier Bullets 69 and above. The 16" barrels can get you there but the drop in velocity is a real factor at those distances. You lose anywhere from 50-100 FPS per inch of barrel. The longer it takes a bullet to get to its target, the longer gravity, wind will effect it. This is where heavy bullets come into play. They dont get effected by wind as much.

Expect minute of 2 man accuracy at 600 yards out of a run of the mill barrel and a nice scope setup with surplus M855.

Thanks!

So I guess my next question is BCM or CMMG?

mltrading
01-30-2009, 2:42 PM
Both 1/7 and 1/9 would work flawlessly for most cases.

What's the variety range of your ammo? The 1/9 would stablize 55gr without problem, as well as heavier SS109. If you plan to shoot very light bullets, 1/7 would tear the bullet apart.

fallenknight308
01-30-2009, 2:59 PM
Both 1/7 and 1/9 would work flawlessly for most cases.

What's the variety range of your ammo? The 1/9 would stablize 55gr without problem, as well as heavier SS109. If you plan to shoot very light bullets, 1/7 would tear the bullet apart.

I would be shooting everything from wolf to win or rem, or mostly this stuff:
http://www.cheaperthandirt.com/AMM223-5.html
Although CTD say its rare.

fusionstar
01-30-2009, 3:32 PM
that stuff is good in 1:7 up to 1:12 barrels. lol.

And that is a horrendous amount to pay for m855.
you can get it for 10-12 dollars a box.

lumpia
01-30-2009, 3:45 PM
Thanks!

So I guess my next question is BCM or CMMG?


Without a doubt, BCM. Way better quality control. CMMG is still good to go though. But for the marginal price difference, BCM is where it's at. Only problem is getting it when they have it in stock. There last batch of LMT uppers sold out in under 15 minutes. The batch I bought my BCM mid-lengths sold out in about an hour. Then you need a bolt, which also sold out in about an hour.

Keep your eye out. There are reports of BCM M4 16" uppers being stocked in the next 7-10 days.

Ahhnother8
01-30-2009, 4:38 PM
If you plan to shoot very light bullets, 1/7 would tear the bullet apart.

Sorry, but that is WRONG.

At .223 velocities, bullets just don't fail. Particularly any type of FMJ. I have shot 40 grain varmint bullets (THIN jackets), VERY fast, out of 1:7.7 Kriegers. And 50 and 55 grain varmint bullets out of 1:7 twist Kriegers. They shoot great!! ALWAYS choose a "too fast" twist over a "too slow" twist, it leaves ALL of your options open for bullet choice. :D

fusionstar
01-30-2009, 4:41 PM
Sorry, but that is WRONG.

At .223 velocities, bullets just don't fail. Particularly any type of FMJ. I have shot 40 grain varmint bullets (THIN jackets), VERY fast, out of 1:7.7 Kriegers. And 50 and 55 grain varmint bullets out of 1:7 twist Kriegers. They shoot great!! ALWAYS choose a "too fast" twist over a "too slow" twist, it leaves ALL of your options open for bullet choice. :D

uh.. they do (varmint bullets)
50 grains are fine in 1:7
and 1:7.7 will shoot 40's easily and so will some 1:7 barrels depending on how hot the load is.

Push the bullet too fast and it will rip itself apart. But the only reason to use these 35/40 grainers are to go as fast as possible.


Here is 35 grain and 40 grain vmax bullets from 1:7 twist

GTJaNHjEa_k

fallenknight308
01-30-2009, 4:54 PM
uh.. they do (varmint bullets)
50 grains are fine in 1:7
and 1:7.7 will shoot 40's easily and so will some 1:7 barrels depending on how hot the load is.

Push the bullet too fast and it will rip itself apart. But the only reason to use these 35/40 grainers are to go as fast as possible.


Here is 35 grain and 40 grain vmax bullets from 1:7 twist

GTJaNHjEa_k

I want to kill two legged beasties:D So that smaller stuff isn't as important as 55gr and up

fusionstar
01-30-2009, 4:56 PM
I want to kill two legged beasties:D So that smaller stuff isn't as important as 55gr and up

haha then any twist faster than 1:9 should suffice.