The data/gelatin pics I promised
I have gotten the gelatin pics from a slide demonstrationg the performance of the 6.8 SPC in comparison with the 7.62x51 and 5.56 NATO standard M855 loadings. However, it had great pics regarding the performance of the 5.56 NATO. The presentationis availible in its entierty here:
http://www.dtic.mil/ndia/2004arms/session3/dennison.ppt
The picture is on this slide:
http://www.dtic.mil/ndia/2004arms/session3/273,11,6.8mm Remington SPC Terminal Performance at 50 yds
The Tests were performed at 50 yards. Also, the 5.56 weapon was a std. M4 (14 in. Barrel), a CAR-15 has a shorter barrel and less performance (obviously)
I am having difficulty finding a pic I once saw of the 7.62x51 tested in the same setup, If you want to try the tests yourself go here:
http://www.firearmstactical.com/tacticalbriefs/volume4/number1/article412.htm
If you do try it please post pics, I would love to see some casual, non-gov affiliated research on these two rounds in a gel test.
And time for the calculable data:
Standard 5.56 M855 load shot sighted at 50 yards, with 1/4 MOA adjustments, at 1000 ft above sea level, in no wind, at 60 deg farenheit, (average measurements) with a 63 gr projectile discharged at 2611 fps out of a 1.5 in barrel (CAR-15). Please note that this is all calculations, I have not used a CAR-15/M177 before and probly never will:
the document with the calculations is 556_CAR15calc.doc
Now for the Standard 7.62x51 NATO loadings. To be fair, its sighted at 50 yards (it would never happen though), with 1/4 MOA adjustments, at 1000 feet above sea level, in no wind, at 60 deg farenheit, discharged at 2580 fps with a 173 gr projectile out of a 22 inch barrel (M21).
The 50 yrd zero is 308_M21calc.doc
the 300 yrd zero is 308_M21calc2.doc
The 5.56 gel test pic: