Building Most Accurate Load for Sig 556

[AntlerAddict]

I am a proud new owner of a sig 556 swat. I've enjoyed hunting and shooting all my life, but i am fairly new to reloading. I'm trying to develop an accurate hunting load for my 556. (I don't need to hear that the 5.56 can't handle hunting) I've decided to use a 70gr Barnes TSX BT for maximum expansion and penetration. My sig has a 1:7 twist so for the most part, the heavier the bullet the better.

I know the gun is accurate. With standard 55gr XM193 i usually get 2-3" groups at 100 yards(not great), but with 75gr hornady TAP, i can get 1" groups all day with my Vortex 4x12x40 scope.

My question is about what powder i should use. I've got a 16 inch barrel, so wouldn't it make sense to use a fast burning powder? I need to get the maximum velocity/energy that i can. I've heard before that all the powder is burned before the bullet leaves the 16 inch barrel, but i'm not sure. Does anyone have any powder recommendations, or even better, some accurate load data with this gun?

Thanks!

 

[Loopm5]

Re: Building Most Accurate Load for Sig 556

Please go and get a Lyman reloading book. Or any reloading book and load to the book specs first.Someone that is new to reloading that might not know its not a good idea to put FAST I.E. Pistol powder in a rifle cartridge. Plus you need to load a powder that is suitable for the gas system you are using. I like AA, AND VIT powders for 5.56. After you learn to load to book spec. then customize your loads.If not it will be very EXPENSIVE both from a new gun standpoint to a big hospital bill.

 

[samnev]

Re: Building Most Accurate Load for Sig 556

Agree, get a few reloading books. Lyman and Sierra come to mind, do you research and go from there. There is a wealth of info in both those manuals.

 

[AntlerAddict]

Re: Building Most Accurate Load for Sig 556

Ok, thanks guys. I have a brother that has reloaded for years, and i will be working with him. I'm not going to start throwing stuff together and praying for the best. Do you know if Lyman and Sierra books would have load data for Barnes Bullets? Barnes' website has two loads listed for that bullet, but i was hoping for a few more i could try.

 

[mforsyth]

Re: Building Most Accurate Load for Sig 556

Hi, New to this site. And I just bought a Stag Arms M8. The rifle shoots beyond me. I am using 23g of AA2230 with a 55g FMJ I also use a 62g FMJ-BT with 25g. I get 1 to 1 1/2 inch groups at 100yrds and it works real well at 300 to 400 yards. I worked up the loads from the Lyman reloading book. I have been reloading for about 35 years. I also use IMR-4895 with 23g. I seat the round to 2.255 OAL.
I am getting about 2900 FPS with the 55g and 2600 FPS with the 62g

 

[smokshwn]

Re: Building Most Accurate Load for Sig 556

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AntlerAddict</div><div class="ubbcode-body">Ok, thanks guys. I have a brother that has reloaded for years, and i will be working with him. I'm not going to start throwing stuff together and praying for the best. Do you know if Lyman and Sierra books would have load data for Barnes Bullets? Barnes' website has two loads listed for that bullet, but i was hoping for a few more i could try. </div></div>

Get a Barnes reloading manual while you're at it

 

[littlerascal56]

Re: Building Most Accurate Load for Sig 556

Spent about 4 weekends working up loads for a Sig556 SWAT. See the best load below. This was with my match brass...don't use brass you want to keep, as the gun beats it to a pulp with just one firing! Use LC and leave it on the ground, as it gets thrown about 30' anyway and is heavily dented and creased.

This is a 5 shot group @ 100 METERS...the gun liked 69SMK's very much.

 

[MeridianNW]

Re: Building Most Accurate Load for Sig 556

+1 on the dinged brass! I have a swat 556 and was quite surprised at how far the brass is slung!

Nice shooting there BigBore56, how big is that center dot (or your group)?

I don't reload (yet) but I am really curious about how far these could reach out there with hand loads. I'm thinking that 69SMK bullet, or something in the 68-78 range would be the way to exploit the range of this rifle.

Have you tested the legs of this sig?

 

[Scottiep504]

Re: Building Most Accurate Load for Sig 556

I have a Sig 556 Swat also and have been working on building an accurate load. This past weekend I was able to get a 3/4" group @ 100yds using, Lake City brass,77gr SMK (HPBT), and 24.4gr of Varget. 24.6gr of Varget also worked very well but 24.4 was the best. The Sig can shoot some pretty tight groups but I did notice a severe decrease in accuracy as the barrel heated up. I also have a "trick" so that your brass doesn't get dented as it's ejected. I had my gun sprayed with a thin coat of rhino liner right around the ejection port. If I could ever figure out how to post pics I would. It came out really nice and keeps my reciever from getting dinged up.

 

[littlerascal56]

Re: Building Most Accurate Load for Sig 556

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MeridianNW</div><div class="ubbcode-body">+1 on the dinged brass! I have a swat 556 and was quite surprised at how far the brass is slung!

Nice shooting there BigBore56, how big is that center dot (or your group)?

I don't reload (yet) but I am really curious about how far these could reach out there with hand loads. I'm thinking that 69SMK bullet, or something in the 68-78 range would be the way to exploit the range of this rifle.

Have you tested the legs of this sig?

</div></div>

The center dot on my targets is 5/8'. I sold the Sig SWAT to upgrade to a Wilson Combat Tactical. It didn't shoot any tighter groups however, but did leave the brass in perfect condition on the ground...right by the rifle.

Sold all my AR-15's and now shoot an Armalite AR-10T. I like it!

 

[MeridianNW]

Re: Building Most Accurate Load for Sig 556

That's a pretty nice grouping, what did you use for sights/optics on it while you had it?

I got the diopter sight set with mine, but I would like some Troy or Magpul folding sights for it.

 

[littlerascal56]

Re: Building Most Accurate Load for Sig 556

I just had a Nikon Monarch 4-16 on that SIG. I did shoot some 2" groups w/55 grainers, so I knew it didn't like those.

It shot 1" groups @100 Meters with Varget or H335...as long as I used 69 SMK's. It also was picky about brass. I had to use a small base sizing die to get the bolt to close, so it had a pretty tight chamber. The SIG's were really built for factory 5.56 ammo, and reloading was somewhat of a challenge. It was a "cool looking" rifle though.

 

[MeridianNW]

Re: Building Most Accurate Load for Sig 556

What kind of riser is that on the stock? I like the looks of that. I'm thinking I'll need a riser or another stock once I put a scope on it. I got the patrol version.

That's a nice looking setup... nice brass catcher too!

Here is mine, I got the matching set, with the little brother 22!

(still... what riser is that?)

 

[littlerascal56]

Re: Building Most Accurate Load for Sig 556

The SWAT model comes with the factory MagPul CTR stock. I just added the optional 3/4" thick MagPul recoil pad and the cheekpiece riser. MagPul makes the risers for the CTR in 3 sizes...1/4", 1/2", and 3/4". They work perfectly on the SIG, as it has the side charging handle vs. rear charging AR-15.

I had mounted that Nikon in a JP mount which was pretty high, and required the 3/4" stock riser.

I prefer to keep the scope tight to the receiver for a better cheekweld. My AR-10T has Medium IOR rings and the 50mm Tactical scope almost touches the forearm. I still had to install a MagPul PRS to get the cheekpiece up about 1/2".

When you set up a rifle to fit you...the groups are much tighter.

 

[MeridianNW]

Re: Building Most Accurate Load for Sig 556

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigBore56</div><div class="ubbcode-body">The SWAT model comes with the factory MagPul CTR stock. </div></div>

Really?! I did not know that... but I do know there are about 7 different flavors of this thing, depending upon the year of mfg and the various models that have been introduced.

Nevertheless I will go do some reasearch on this. Thanks BigBore!

In fact, now that I look at our rifle pics a little more closely I see you do not have the newer folding stock like mine. I think you got the swiss style which gives you the Magpul options... hmmm...