.223 bullet weight for 1:7 Twist Sig 556

west5757 · November 8, 2012, 03:02 PM

I have a Sig 556 with a 1:7 twist. When I sighted it in I was all over the place with 55 grains. I got a box of 64 grainers and it made a lot of difference.

I was wondering if anyone has found the optimal weight for this gun?

RickB · November 8, 2012, 03:09 PM

The 1:7 twist was adopted along with the then-new 62gr G.I. load, so I would expect it to be optimal for bullets of that weight.
I have a 1:7 AR, and can consistently break clay birds at 200 yards with 55gr ammo, which must be better than "all over the place" accuracy?

pturner67 · November 8, 2012, 03:15 PM

West5757, what distance are you shooting?

My 1:7 does great with anything 55-77 grain but it's rare I go past 100 yds.

Crow Hunter · November 8, 2012, 03:19 PM

Are you comparing 55gr XM193 or Wolf ammo to premium 64gr hunting ammo?

If so, that really isn't a good comparison.

west5757 · November 8, 2012, 03:31 PM

Rick B... I could hit clays at 80-100 yards when I sighted it in with 55 grain...maybe. It would be close.

pturner... I shoot mainly 100 yds or less.

Crow Hunter... I was shooting cheaper ammo. That does make a difference.

When I sighted it in I thought maybe my scope was off or something. I was frustrated. The next day I got heavier grain bullets and the difference was amazing. I'm getting some 64 grain soft tips today (that's all that is available locally) and trying that out.

Metal god · November 8, 2012, 04:36 PM

I have an AR with 16" 1-7 , free floated barrel with a red-dot . It shoots well at 50 yards about 4MOA = 2" groups at 50yds. I wanted to find out how accurate the gun really was so I put a scope on it and tested it out . I shot PMC , x193 , Privi , some kind of winchester all 55gr and I had some 77gr federal gold metal match . All the 55gr stuff was around 3MOA @ 100yds ( thats with a 3-9x40 scope

)but the heavier match stuff I could shoot just about 1 MOA with .

IMO if you want to find out how accurate your gun really can be you will need to get some good ammo . 55gr and up should be fine for your rifle but the heavier you go the better it should be .

There is one other thing . If you have a stock mil-spec trigger you are going to have to really concentrate on your trigger pull . they do not lend them selfs to accurate shooting .

Sweet Shooter · November 8, 2012, 04:40 PM

Someone here told me "Sometimes things that are not supposed to work often do". I have a SIG 400... 1x7 It shoots 40gr V-Max like this:
-SS-

Metal god · November 8, 2012, 05:04 PM

Sweet shooter thats a sweet group

November 8, 2012, 03:02 PM	#1
west5757 Member Join Date: September 10, 2012 Posts: 49	.223 bullet weight for 1:7 Twist Sig 556 I have a Sig 556 with a 1:7 twist. When I sighted it in I was all over the place with 55 grains. I got a box of 64 grainers and it made a lot of difference. I was wondering if anyone has found the optimal weight for this gun?

November 8, 2012, 03:19 PM	#4
Crow Hunter Senior Member Join Date: January 27, 2012 Posts: 1,078	Are you comparing 55gr XM193 or Wolf ammo to premium 64gr hunting ammo? If so, that really isn't a good comparison. __________________ I am no longer participating in gun forums. Good luck.

November 8, 2012, 04:36 PM	#6
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	I have an AR with 16" 1-7 , free floated barrel with a red-dot . It shoots well at 50 yards about 4MOA = 2" groups at 50yds. I wanted to find out how accurate the gun really was so I put a scope on it and tested it out . I shot PMC , x193 , Privi , some kind of winchester all 55gr and I had some 77gr federal gold metal match . All the 55gr stuff was around 3MOA @ 100yds ( thats with a 3-9x40 scope )but the heavier match stuff I could shoot just about 1 MOA with . IMO if you want to find out how accurate your gun really can be you will need to get some good ammo . 55gr and up should be fine for your rifle but the heavier you go the better it should be . There is one other thing . If you have a stock mil-spec trigger you are going to have to really concentrate on your trigger pull . they do not lend them selfs to accurate shooting . __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

November 8, 2012, 04:40 PM	#7
Sweet Shooter Senior Member Join Date: June 17, 2011 Posts: 672	Someone here told me "Sometimes things that are not supposed to work often do". I have a SIG 400... 1x7 It shoots 40gr V-Max like this: -SS- Last edited by Sweet Shooter; December 18, 2014 at 06:09 PM.

November 8, 2012, 05:04 PM	#8
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,876	Sweet shooter thats a sweet group __________________ If Jesus had a gun , he'd probably still be alive ! I almost always write my posts regardless of content in a jovial manor and intent . If that's not how you took it , please try again .

November 8, 2012, 03:09 PM	#2
RickB Senior Member Join Date: March 1, 2000 Location: Boise, ID Posts: 8,518	The 1:7 twist was adopted along with the then-new 62gr G.I. load, so I would expect it to be optimal for bullets of that weight. I have a 1:7 AR, and can consistently break clay birds at 200 yards with 55gr ammo, which must be better than "all over the place" accuracy?

November 8, 2012, 03:15 PM	#3
pturner67 Senior Member Join Date: February 26, 2006 Posts: 737	West5757, what distance are you shooting? My 1:7 does great with anything 55-77 grain but it's rare I go past 100 yds.

November 8, 2012, 03:31 PM	#5
west5757 Member Join Date: September 10, 2012 Posts: 49	Rick B... I could hit clays at 80-100 yards when I sighted it in with 55 grain...maybe. It would be close. pturner... I shoot mainly 100 yds or less. Crow Hunter... I was shooting cheaper ammo. That does make a difference. When I sighted it in I thought maybe my scope was off or something. I was frustrated. The next day I got heavier grain bullets and the difference was amazing. I'm getting some 64 grain soft tips today (that's all that is available locally) and trying that out.