09-10-2013, 07:17 PM
cory Wrote:By just how much velocity are they beating us? What is 6.8 average velocity for a 130gr projectile from a ~20" barrel?
To do a fair comparison to the Grendel 123gr bullet I believe we need to use a 6.8 130gr bullet.
This is how I came about that.
6.8 Comparison Projectile(gr) = (Grendel Projectile(gr)/6.5(mm))*6.8(mm)
It would be nice to make the numbers look better if you use a heavier bullet in the faster rifle and a lighter one in the slower one but if you use the same weight bullets out of the same length and type barrels both handloaded to max safe levels the 6.8 consistently produces apx 100fps more than the 264/Grendel. Factory ammo pressures are all over the map from 45k psi to 55k PSI but if that is all one shoots then that is what should be compared.
Figure thrust on the bullet to understand why there is some improvement with a larger bore. Area of a .264 bullet VS area of a .277 bullet just like guys here figure thrust on the bolts because the G case is larger dia. The larger dia bore allows the use of faster burning powders, the extra thrust and shorter bullets creating less resistance =more velocity.
I've been shooting both with the same 5R rifling since 2007 side by side using the same method to determine max loads.
Out to 300yds both are very close, after that the higher BCs of the .264 bullets help keep the velocity up making it a better long range target round.