The actual difference between 6.8 SPC-II and 6.8 SPC SAAMI is at most about 30 fps.
A number of tests have been done in private by the industry, and I got permission to make one public. It backs up the other data from multiple carefully done studies.
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From: Robert Silvers
Sent: Thursday, July 14, 2011 5:06 PM
To: Johan Loubser
Subject: Re: Western Powders Ballistic lab
Johan,
Have you ever done a test where you take a 6.8 SPC SAAMI test barrel, measure velocity and pressure, then ream the same barrel to 6.8 SPC-II - and add more powder to match the pressure of the previous test, and then see how much extra velocity there is?
Robert.
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Robert,
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 6.98Spc is not sensitive to the slight changes in dimensions between the std and SPEC II.
Regards
Johan Loubser
Ballistician
Ramshot.Accurate.Powders
----------------------------------
Robert,
Example is that with SAAMI reference ammunition we got a difference of Pressure: -2.5%/-1200Psi and -19Fps
If one consider that is equal or less than one standard deviation I consider it negligible.
Regards
Johan Loubser
Ballistician
Ramshot.Accurate.Powders
A number of tests have been done in private by the industry, and I got permission to make one public. It backs up the other data from multiple carefully done studies.
----------------------------------
From: Robert Silvers
Sent: Thursday, July 14, 2011 5:06 PM
To: Johan Loubser
Subject: Re: Western Powders Ballistic lab
Johan,
Have you ever done a test where you take a 6.8 SPC SAAMI test barrel, measure velocity and pressure, then ream the same barrel to 6.8 SPC-II - and add more powder to match the pressure of the previous test, and then see how much extra velocity there is?
Robert.
----------------------------------
Robert,
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 6.98Spc is not sensitive to the slight changes in dimensions between the std and SPEC II.
Regards
Johan Loubser
Ballistician
Ramshot.Accurate.Powders
----------------------------------
Robert,
Example is that with SAAMI reference ammunition we got a difference of Pressure: -2.5%/-1200Psi and -19Fps
If one consider that is equal or less than one standard deviation I consider it negligible.
Regards
Johan Loubser
Ballistician
Ramshot.Accurate.Powders