Are muzzle velocities comparable between different projectiles of the same weight?

[ARH77]

Hi,

Ok starting off with the example, seems easier then to write a lot to start.

Example - 308 rifle - 1-11 twist - 26" length - Same exact rifle used for both loads;

185 Lapua Scenar = 2650 fps (safe load)

185 Berger Hybrid = ???? same speed with safe load? (powder weight adjusted)

Can I safely assume that if I changed to a 185 Berger Hybrid that I'd get 2650 fps (safe load) +/- 25 fps with knowing that I can have already got 185 Lapua Scenar's to 2650 fps in that rifle? I know powder weight might need to be slightly adjusted.

**These aren't the exact bullets I'm looking at shooting just an example.

 

[Hitzy]

Bullets of the same weight and construction should leave the muzzle pretty close to the same speed.

 

[tootall]

Muzzle vel should be close, downrange vel may differ due to different drag numbers.

Muzzle may not be identical due to longer bearing surfaces etc.

 

[Mystic Precision]

Your rule of thumb with bullets of similar form factor is correct.

However, the Hybrid and scenar form factors are quite different. The Lapuas have far more bearing surface so will have more bore drag vs the Hybrids.

As a rule of thumb, at equal pressures, the Hybrids will go faster then traditional bullet shapes... doesn't mean that is the ACCURATE velocity.

Best to shoot them over a chronograph if you really want to be sure.

Good luck.

Jerry

 

[Andy]

Your rule of thumb with bullets of similar form factor is correct.

However, the Hybrid and scenar form factors are quite different. The Lapuas have far more bearing surface so will have more bore drag vs the Hybrids.

As a rule of thumb, at equal pressures, the Hybrids will go faster then traditional bullet shapes... doesn't mean that is the ACCURATE velocity.

Best to shoot them over a chronograph if you really want to be sure.

Good luck.

Jerry

I agree that the only way to know is to use a chrony.

I understand though that you should still expect close MV's, as with the same load the bullet with greater bearing surface will yield higher pressures, so the pressure will not be the same, even over the same powder load.