03-04-2013, 04:15 AM
Bill makes a valid point, and one that has been brought up here over the years: Without a specific requirement, we're not even chasing moving goal posts. There isn't a defined playing field.
Basing an army's service carbine selection on some of the preferences of marginal units who have entirely different mission profiles, with insane amounts of support behind them compared to conventional units, isn't a sensible approach. If you are doing a direct action raid, with helo insertion and extraction, you can go in with minimal kit and a basic load minus. 5 mags is usually more than enough to get it done for an SF team, with a few to hold off any contingencies if things get nasty and you need an immediate exfil.
For joe tentpeg in the line, who doesn't have that kind of helo or priority CAS support, (5) 20rd mags might get him through one contact, with a mag or two to die in-place or wait for relief, taxing the system. We all tried that (US, British, Germans, etc.), and it just doesn't cut the mustard for units that need to be able to continue mission after contact.
Negative again. You don't need a 24" barrel to get the 6.5 Grendel to do what you want. 16" is more than plenty. I'm not making this up. It doesn't take a lot to get a 16" Grendel to push 123gr projectiles at 2600fps. I've had factory ammo that clocked 2583fps out of mine with a commonly available powder, not a purpose-built powder. With a stronger bolt and extension, you can run the pressures at 55,000psi and use an industrial powder specifically designed to meet the unspecified requirements that nobody has mapped out yet.
You don't need more capacity, just the right powder. We already have guys who have used Hodgdon's CFE to push 130gr Norma Golden Targets at 2700fps with just a slightly longer COL from modified polymer mags.
Velocity is the biggest wounding mechanism, combined with bullet construction. A thin jacket with lead core will fragment above a certain velocity threshold. Once it falls below that, you then have to rely on construction. Yawing may or may not happen depending on tissue integrity, anatomical landmark penetration angle, and internal anatomical arrangement along the wound channel.
Let me reinforce that no longer case is needed than what we have already. Projectile weight, construction, and velocity can only be addressed once we have a specific set of requirements. Do you go 100gr solid sectional bullet for an assault rifle/dual-purpose load at 2950fps? Do you go with a 130gr LMG load at 2700fps designed to penetrate? Without any specific requirements, we're spinning wheels.
There are existing loads that will fill the DM role that the UK is currently using the L129A1 in, but that adds another caliber to the system. I've also played with the L85A2, and the 16" LMT is a beast compared to it. The extra 4" of barrel that needs to be 1.25" dia. adds a ton of weight to that pig of a carbine.
Quote:Most operators have now swapped these for HK417s with 16 barrels. Apparently, they love it. They can shoot out to 600 meters and equally use it in close quarter house clearing. H&K have done a great job damping the recoil so in extreme circumstances, firing automatic bursts isnt an issue. And, perhaps most important of all, there are no issues with the terminal effectiveness of 7.62 mm ammunition. Ah, I said, but isnt the HK417 quite a bit heavier than the C7?
Basing an army's service carbine selection on some of the preferences of marginal units who have entirely different mission profiles, with insane amounts of support behind them compared to conventional units, isn't a sensible approach. If you are doing a direct action raid, with helo insertion and extraction, you can go in with minimal kit and a basic load minus. 5 mags is usually more than enough to get it done for an SF team, with a few to hold off any contingencies if things get nasty and you need an immediate exfil.
For joe tentpeg in the line, who doesn't have that kind of helo or priority CAS support, (5) 20rd mags might get him through one contact, with a mag or two to die in-place or wait for relief, taxing the system. We all tried that (US, British, Germans, etc.), and it just doesn't cut the mustard for units that need to be able to continue mission after contact.
Quote:So, if a 6.5 mm Grendel round can match 7.62 mm velocity and retained energy at 600 meters, then its on target. In fact beyond that range, thanks to its more aerodynamic bullet, it will overtake 7.62 mm and out perform it at longer ranges. Based on the data I have seen, a 6.5 mm Grendel will only do this in a weapon with a 24-inch barrel.
Negative again. You don't need a 24" barrel to get the 6.5 Grendel to do what you want. 16" is more than plenty. I'm not making this up. It doesn't take a lot to get a 16" Grendel to push 123gr projectiles at 2600fps. I've had factory ammo that clocked 2583fps out of mine with a commonly available powder, not a purpose-built powder. With a stronger bolt and extension, you can run the pressures at 55,000psi and use an industrial powder specifically designed to meet the unspecified requirements that nobody has mapped out yet.
Quote:The current Grendel cartridge is right at the limit of its capacity and the bullet is long. I dont see any way of of putting more propellant behind the current 6.5 bullet (which has an almost perfect G7 FF and G7 BC) without slightly increasing case capacity.
You don't need more capacity, just the right powder. We already have guys who have used Hodgdon's CFE to push 130gr Norma Golden Targets at 2700fps with just a slightly longer COL from modified polymer mags.
Quote:The wounding mechanism has to do with bullet construction as much as shape. One issue with 7.62 mm NATO is that it doesn't yaw rapidly in soft tissue. Of course, it doesn't need to, because it makes a pretty large hole without upsetting.
Velocity is the biggest wounding mechanism, combined with bullet construction. A thin jacket with lead core will fragment above a certain velocity threshold. Once it falls below that, you then have to rely on construction. Yawing may or may not happen depending on tissue integrity, anatomical landmark penetration angle, and internal anatomical arrangement along the wound channel.
Let me reinforce that no longer case is needed than what we have already. Projectile weight, construction, and velocity can only be addressed once we have a specific set of requirements. Do you go 100gr solid sectional bullet for an assault rifle/dual-purpose load at 2950fps? Do you go with a 130gr LMG load at 2700fps designed to penetrate? Without any specific requirements, we're spinning wheels.
There are existing loads that will fill the DM role that the UK is currently using the L129A1 in, but that adds another caliber to the system. I've also played with the L85A2, and the 16" LMT is a beast compared to it. The extra 4" of barrel that needs to be 1.25" dia. adds a ton of weight to that pig of a carbine.