12-02-2013, 03:42 PM
The 130 grain interest comes from the notion that retained energy is an important parameter for projectile effectiveness. It is not.
The closest the total energy at impact comes to having a significant effect is the sound and size of splash heard and seen by troops near it. This is, at best, a weak argument mostly because any splash or noise will get their attention if they know that serious or lethal injury will result if they get hit.
We know that bullets of weighing 60 grains or more are highly effective on live targets.
The remaining issue is total penetration through timbers and hard targets. Here the useful metrics are the momentum and momentum densities which are the sectional densities multiplied by the velocity or square of the velocity.
The 6.5 does very well, especially at long ranges. compared to the 7.62 Russian and 7.62 NATO when these metrics are employed.
Hence, we can go with a green bullet weighing 95-100 gr for an infantry carbine and 110-120 gr for the LMG.
We might not need to invoke a longer COL for the LMG -- just accept pressures of 55,000 to 60,000 psi to get excellent long range performance. This would maintain emergency ammunition interoperability to cover those exceedingly rate events when one type or another is not available.
The closest the total energy at impact comes to having a significant effect is the sound and size of splash heard and seen by troops near it. This is, at best, a weak argument mostly because any splash or noise will get their attention if they know that serious or lethal injury will result if they get hit.
We know that bullets of weighing 60 grains or more are highly effective on live targets.
The remaining issue is total penetration through timbers and hard targets. Here the useful metrics are the momentum and momentum densities which are the sectional densities multiplied by the velocity or square of the velocity.
The 6.5 does very well, especially at long ranges. compared to the 7.62 Russian and 7.62 NATO when these metrics are employed.
Hence, we can go with a green bullet weighing 95-100 gr for an infantry carbine and 110-120 gr for the LMG.
We might not need to invoke a longer COL for the LMG -- just accept pressures of 55,000 to 60,000 psi to get excellent long range performance. This would maintain emergency ammunition interoperability to cover those exceedingly rate events when one type or another is not available.