New Cartridge Developments and Implications for Dismounted Infantry Soldiers

[bwaites]

I accept what they said as being true, insofar as it went. I don't feel like going back and rereading the two or three threads on the subject so as to link to verifying posts, but here is what I recall:

• Silvers said that to his knowledge, SPCII ammo had not been tested in the manner he described Loubser doing. That is, firing in a SAAMI chamber, then reaming the chamber to SPCII and firing again. Silvers agreed that testing SPCII ammo in this manner is something that really should be done in order to establish what differences there are in velocity and pressure.
  
  
  
• Roberts carefully avoided saying anything about what type of load(s) had been used in the pressure tests to which he alluded.
  

Indeed.

I'm admittedly belaboring the point, but it doesn't REALLY matter what load you are using. If they saw less than a 30 FPS and 1500 PSI difference, in a SPCII chamber, than stepping up the load to anything short of a magnum load isn't going to bring that back to the results the SPCII adherents are claiming.

Lets say the SAAMI load produced 55,000 PSI in the standard chamber, and 53,500 PSI in the SPCII chamber. That means that just to MATCH the SAAMI load from a SAAMI chamber to an SPCII will require a load that would produce close to 56,500 PSI in a SAAMI chamber.

Then you want to increase velocity by 200 FPS or so? That's going to require a load that would run somewhere in the 62,000 or better range, comparing the 6.8 SAAMI and SPCII loads.

Not real likely that any manufacturer is going to put that one into production!

To get higher velocity, you need higher pressure, and to get pressure from a longer throat requires more powder, which is in short supply in these little cases!