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View Full Version : .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 :D