Hi,

I am a student doing a project in physics about guns. I need to be able to calculate the ballistic coefficient of the NATO 5.56 SS109 round compared to the standard round (apparently SS109 is 25% heavier). However, I need the drag coefficient.

Based on the selections given here
http://www.frfrogspad.com/drgshape.htm

Which drag form should I use for this round? g1, g7, etc. I figure someone in here must be familiar with the round. I hope this is the correct topic forum for my post. Thank you all very much for the help!

Start here

http://ammo.ar15.com/

Hopefully your instructor is not an anti-gun flaming liberal who will take your answer and transform it to the liberal side and then have the question, ....................."Is that round "humanitarian"??" Hey folk, if you need to shoot something or somebody............where the hell does "humanitarian" come into the eqaution???????GHD

Nah he's a good guy...just tells it like it is

Hopefully you already have an anwser to this but if not here's mine:
For example, using Nosler Ballistic Tip (boat tail spitzer) bullets for comparison, the 150 grain .30 caliber bullet has a BC of .435. The 95 grain .243 bullet has a BC of .379. The 55 grain bullet for the 5.56mm NATO has a BC of only .267, despite its streamlined appearance.

At typical 5.56mm velocities, this bullet's lateral drift at 300 yards in a light 10 MPH crosswind is 14.2 inches. This is enough to blow a perfectly aimed bullet completely off a man-size target! The 5.56mm 62 grain FMJ-boat tail spitzer has a BC of .307. This is still very inferior to the BC of the .243's 95 grain bullet. At typical .243 velocities, the 95 grain bullet's lateral drift at 300 yards in a 10 MPH crosswind is about 6.3 inches.

and here's my source:
http://www.chuckhawks.com/243_service_rifle.htm

Personally I'd use these numbers and fudge my calculations but do whatever you feel conforms to the standards of "academic integrity"