07-27-2011, 06:15 PM
OK, as a complete civilian newbie, can I point a couple of things out?
1) Multiple sources now report that SAAMI II chambering for the 6.8 SPC and the associated ammunition does not safely provide the upgrade that the SAAMI II advocates have promised. In fact Dr. Roberts has stated; "Every professional ballistics facility, including USG, foreign military, and Industry, that I am aware of that has tested 6.8 SPC vs. 6.8 SPCII using industry standard equipment has reported only a 1000-1500 psi change." This is confirmed by Johan Loubser at AA/Ramshot powders; "Yes we did exactly that and the difference was negligible as to be ignored ca 20-30Fps and <1000Psi.
I know there is a lot of claims out there regarding this. Some apply the effects of other calibers (such as the 223Rem) with completely different expansion ratios to the 6.8SPC.
The 6.8Spc is not sensitive to the slight changes in dimensions between the std and SPEC II."
So the SpecII chamber simply doesn't give the advantages proposed.
2) As I understand it, barrels are not the issue with sustained fire, gas tubes are. There is a very good video online demonstrating what happens to an AR with prolonged auto firing, and the gas tube is destroyed first, leaving the shooter with essentially a straight pull bolt action rifle.
Here is the Colt test, note the sound deadening used in the test tunnel in the background!: http://www.youtube.com/watch?v=Kzfm4pYhIyY
So I simply don't think that adding a better/heavier barrel will solve the issue, the weak link appears to be the gas tube, not the barrel. It may be true that repeated auto fire that approaches but does not cause gas tube failure might cause the barrel to become progressively damaged, decreasing accuracy, but any M4/M16 variant being used that way isn't going to be used as a long range sniper rifle anyways!
1) Multiple sources now report that SAAMI II chambering for the 6.8 SPC and the associated ammunition does not safely provide the upgrade that the SAAMI II advocates have promised. In fact Dr. Roberts has stated; "Every professional ballistics facility, including USG, foreign military, and Industry, that I am aware of that has tested 6.8 SPC vs. 6.8 SPCII using industry standard equipment has reported only a 1000-1500 psi change." This is confirmed by Johan Loubser at AA/Ramshot powders; "Yes we did exactly that and the difference was negligible as to be ignored ca 20-30Fps and <1000Psi.
I know there is a lot of claims out there regarding this. Some apply the effects of other calibers (such as the 223Rem) with completely different expansion ratios to the 6.8SPC.
The 6.8Spc is not sensitive to the slight changes in dimensions between the std and SPEC II."
So the SpecII chamber simply doesn't give the advantages proposed.
2) As I understand it, barrels are not the issue with sustained fire, gas tubes are. There is a very good video online demonstrating what happens to an AR with prolonged auto firing, and the gas tube is destroyed first, leaving the shooter with essentially a straight pull bolt action rifle.
Here is the Colt test, note the sound deadening used in the test tunnel in the background!: http://www.youtube.com/watch?v=Kzfm4pYhIyY
So I simply don't think that adding a better/heavier barrel will solve the issue, the weak link appears to be the gas tube, not the barrel. It may be true that repeated auto fire that approaches but does not cause gas tube failure might cause the barrel to become progressively damaged, decreasing accuracy, but any M4/M16 variant being used that way isn't going to be used as a long range sniper rifle anyways!
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt