My newest AR is an LWRC DI.  Have upgraded some of my gear, in particular retiring one of my older ACOGs for a new TA31-D-100581, which has a horseshoe/1km range.  Naturally, I've added some other gear, having found that the newer Fiocchi 5.56x45mm M855 (SS109) is a boat tailed spitzer, w/steel penetrator.  The boat tail should give better ballistic performance, but have been unable to find specifics.  Will be dialing-in via Kestrel 5700 Ballistics Weather Meter, Sig Sauer KILO 2400 ABS, and Hornady 4DOF.  Will attempt to do same with Federal 5.56 62 Gr MK318 MOD-0 SOST T556TNB1.

Does anybody know how to acquire relevant G1 and/or G7 for both bullets?

Any and all help greatly appreciated.

Thanks!

I just ordered a thousand rounds of that, so in for the response.

If you go here, you can scroll down & find 2 spreadsheets you can download that address both G1 & G7 tables, at least for your M855/SS109 projectiles.
I'll save your digging (the sheet isn't sorted very well) & let you know that your true SS109 projectile is going to be G1 of .325 & G7 value of .158.  The regular 62gr M855 is .301 & .151 respectively, G7 regarded as more accurately reflecting modern projectile characteristics.  YMMV after that due to tiny atmospheric changes, other mojo & whether the counter-clockwise Nork satellite is passing overhead.  Have fun.


Edit: removed ref to M-193 reticle since OP's specific reticle not same as my standard TA31-D

Just use the center dot and zero at 100. Use the bdc and M855 and Mk318 will shoot almost the same out to 300

After dancing with Federal, who sent me specs on their 55gr XM193LC1A1, of .246 (G1),

someone else, also Federal, sent me their G1 for XM855LC1AC1, which is .349.

This would be an indicator of better performance, distance and wind-bucking ability.  This will

help when plugging variables into your ballistics apps...  In my case, Hornady 4DOF, Kestrel

7400 Elite Ballistics Weather Meter, and Sig Sauer KILO 2400 ABS, in conjunction with my

new ACOG  TA31-D-100581.

Hope this helps!

Grain of salt unless someone like Bryan Litz is supplying the numbers, ime

Bryan Litz is the best.  Have his books, and his app for Android.  He works in conjunction with Sig and Kestrel.  Best of all worlds!

G7 for 5.56 is kinda pointless, since G7 really comes into play from 600yds on out.

Your barometric pressure input into a program with G1 will give you all you need for 5.56 within its realistic engagement range.

Just to throw some other numbers out there, CBC/Magtech told me that their M193 load has a G1 of .272 and their 62gr fmj is .340

0.151 G7 BC is the typical reference for M855/SS109.

G7 is always better to use then G1, as the G1 # changes depending on velocity.

For example, this is the "G1" for the 77gr SMK:

.372 @ 3000 fps and above
.362 between 2500 and 3000 fps
.362 between 1700 and 2500 fps
.343 @ 1700 fps and below