using m855 ammo with a ballistic coefficient of .301 and a muzzle velocity of 3069, and assuming 0 sight offset, which at 25-50 yards is going to be a much bigger problem than arc. find your sight offset and go use the calculator with that added in.
10 yards: 0.18
20 yards: 0.32
30 yards: 0.43
40 yards: 0.49
50 yards: 0.52
60 yards: 0.5
70 yards: 0.44
80 yards: 0.34
90 yards: 0.19
100 yards: 0
125 yards: -.069
150 yards: -0.168
175 yards: -0.3
200 yards: -0.466
here is the tool:
http://www.handloads.com/calc/
Edited for readability.....
one more thing: is your sig chambered for 5.56x45 or .223? there is a difference. if its chambered for 5.56 then you can shoot both (5.56 will be more accurate), but if it is chambered for .223, then i suggest you do not shoot milsurp 5.56 ammo through it.
this is why. 5.56 ammo is allowed to have a max chamber pressure of 63,000 psi. the chambers manufactured for 5.56 can all withstand that pressure and then some. .223 ammo, on the other had, is rated at 55,000 psi, and the chambers are made accordingly.
so say you have a hot load of 5.56 and it hits 70,000 psi. not supposed to happen, but it does. if you are shooting out of a barrel designed for 5.56, it'll hold up fine. if it was being fired out of a .223 barrel....well, maybe, maybe not. even if the barrel is rated at 20% overpressure, that is still only 66k psi it can handle.
basically, its dangerous. with that said, most manufacturers these days are smart enough to make all barrels capable of handling the increased pressure just in case. i would still not recommend shooting 5.56 out of your .223 caliber rifle, if thats what you have.
