I notice a lot of people questioning the difference between the 260 Rem and the 6.5X55 here and on other forums. The general thought seems to be the Swede case appears larger so the velocities it can achive must be higher. In real life though the Swede isn`t large enough to gain any notable amount of speed over the 260, even at similar pressure. I meausured both cartridges today, both were fired unsized primed Remington brass on my Pact digital. The readings I recorded are as follows;
6.5X55
178.1 gr empty and 236.5 gr full to mouth lip; = 58.4gr water
260 Rem
167.9 gr empty and 222.9 gr full to mouth ip; = 55 gr water
3.4gr total variation
I also looked at my own findings on both cartridges in my records as to velocity with similar loads. The rifles were a M700 DBL in 260 Rem and a Mark X with a Hart bbl chambered for the 6.5X55, both barrels are 24". The results might suprise some.
6.5X55 140 gr Nosler Competition HP
46.0 gr H4831sc
WLR
2595 fps @ 44,612 PT
260 Rem 140 Nosler Competition HP
46.0 gr H4831sc
WLR
2599 fps @ 43,609 PT
another load with the 129gr Hornady SP
6.5X55
46.0gr R19
WLR
2755 fps @ 44,408 PT
260 Rem
46.0 gr R19
Rem 9 1/2
2706 fps @ 43,609 PT
The underlined "PT" figures are readings from a Pressure Trace unit. They ARE NOT PSI. The numbers are raw figures from the unit and not representative of any specific unit of measure. They are however a fair comparison of the pressures produced in each cartridge. All velocity/pressure numbers are the average of 5 shots.
You can see the velocities are very close and the pressure appears to be very similar in each case. I have never ran each to max pressure with similar loads to say the Swede will or won`t excede the 260 or by how much but I doubt there will be much difference if any. Certainly not enough to say one is flatter shooting, more deadly, or in anyway a better cartridge IMHO.
Another way to view this is to look at a reloading manual such as Speer or Nosler. Speer states in theirs the pressures are held to a max of 50K CUP not the 46K CUP SAAMI recommends, and not to use in old rifles without reducing charges. Nosler simply says to use only in modern firearms in good condition, hmmm.
CIP gives the Swede a max PSI piezo of 55,100 psi instead of 48K psi for SAAMI. I`m not sure but I would suspect Speer and Nosler both are holding pretty darn close to CIP figures. SAAMI lists the 260 at 60,000 PSI piezo or about 4,900 psi more then the 6.5X55s CIP.
Studying the Speer #13 data shows the Swede useing 1-2 gr more of the same powder in most max loads for up to 100 fps less velocity. Nosler shows a similar trend. IMHO the best argument in favor of one over the other, is if the shooter was set on a long or short action and wanted the cartridge to fit it properly.
Your findings may vary, and you`re free to disagree. This is only a sample of one...
6.5X55
178.1 gr empty and 236.5 gr full to mouth lip; = 58.4gr water
260 Rem
167.9 gr empty and 222.9 gr full to mouth ip; = 55 gr water
3.4gr total variation
I also looked at my own findings on both cartridges in my records as to velocity with similar loads. The rifles were a M700 DBL in 260 Rem and a Mark X with a Hart bbl chambered for the 6.5X55, both barrels are 24". The results might suprise some.
6.5X55 140 gr Nosler Competition HP
46.0 gr H4831sc
WLR
2595 fps @ 44,612 PT
260 Rem 140 Nosler Competition HP
46.0 gr H4831sc
WLR
2599 fps @ 43,609 PT
another load with the 129gr Hornady SP
6.5X55
46.0gr R19
WLR
2755 fps @ 44,408 PT
260 Rem
46.0 gr R19
Rem 9 1/2
2706 fps @ 43,609 PT
The underlined "PT" figures are readings from a Pressure Trace unit. They ARE NOT PSI. The numbers are raw figures from the unit and not representative of any specific unit of measure. They are however a fair comparison of the pressures produced in each cartridge. All velocity/pressure numbers are the average of 5 shots.
You can see the velocities are very close and the pressure appears to be very similar in each case. I have never ran each to max pressure with similar loads to say the Swede will or won`t excede the 260 or by how much but I doubt there will be much difference if any. Certainly not enough to say one is flatter shooting, more deadly, or in anyway a better cartridge IMHO.
Another way to view this is to look at a reloading manual such as Speer or Nosler. Speer states in theirs the pressures are held to a max of 50K CUP not the 46K CUP SAAMI recommends, and not to use in old rifles without reducing charges. Nosler simply says to use only in modern firearms in good condition, hmmm.
CIP gives the Swede a max PSI piezo of 55,100 psi instead of 48K psi for SAAMI. I`m not sure but I would suspect Speer and Nosler both are holding pretty darn close to CIP figures. SAAMI lists the 260 at 60,000 PSI piezo or about 4,900 psi more then the 6.5X55s CIP.
Studying the Speer #13 data shows the Swede useing 1-2 gr more of the same powder in most max loads for up to 100 fps less velocity. Nosler shows a similar trend. IMHO the best argument in favor of one over the other, is if the shooter was set on a long or short action and wanted the cartridge to fit it properly.
Your findings may vary, and you`re free to disagree. This is only a sample of one...