03-02-2013, 08:00 PM
As it is, the Grendel could replace 5.56 mm tomorrow and be a comprehensively better system - but it cannot replace 7.62 mm, so this larger calibre would need to be retained. The opportunity not to miss is that with not much more development work, the Grendel could easily replace both 5.56 mm and 7.62 mm.
This is important. It is a hard sell to get Big Army to adopt a calibre that is heavier than 5.56 mm, but if the weight saving versus 7.62 mm approaches 25%-30% then it becomes compelling. This is the challenge of Grendel development: match 7.62 mm close enough for 6.5 mm to replace this larger calibre as well as 5.56 mm, with the added benefits of simplified battlefield logistics, simplified procurement, lower training requirements and lower spare parts costs.
So what to do? There is nothing wrong with the design of the 6.5 mm bullet. For EU armies however, it's OTM construction isn't acceptable. Design a steel-core projectile with the same G7 FF and BC in a FMJ design that yaws rapidly in soft tissue and you'll be able to pierce level III and IV body armour, which NATO 7.62 M80 ball and NATO 5.56 mm M855 / SS109 presently struggle to do at longer ranges - then you're in business. The present 6.5 mm bullet often doesn't yaw quick enough. The bullet also needs a cannelure to ensure reliable operation in machine guns. Cannelures aren't very good for aerodynamic efficiency. So a military spec 6.5 mm bullet is likely to lose energy more rapidly than its civilian OTM counterpart. Let's not forget that mass-produced military ammo is generally less good than match quality ammo.
This brings us to job two. I believe the Grendel case needs to extended by 10%-15% to give it the extra powder capacity to to get it to MV of around 900 mps when fired from 16" barrels - entirely possible with a 7 g bullet. This results in a cartridge that is identical to what we have now but is slightly longer at around 64 mm. This would very similar to the 6 mm SAW round of the 1970s except for the fact that the calibre is slightly larger. Give the case a less pronounced shoulder to aid MG feeding and extraction and you make it even better.
The big issue here is that as soon as you extend the cartridge length, you need an AR10 platform not an AR15 platform. Since current Grendel weapons are close to the limit of the AR15's limits, that might not be a bad thing. Let's not forget that military shooting can be much more testing on a weapon's components than shooting foxes in your back yard. A heavier weapon also helps mitigate felt recoil, but the overall weight should be somewhere between an AR15 and an AR10, say 3.8 kgs. In a machine gun, however the weight saving would be considerable. A 7.62 mm Minimi converted to 6.5 mm could weigh less than 8 kg. Compared to an 11-12 kg MAG 58 GPMG in 7.62 mm and that's very worthwhile. And let's not forget, reducing the MG ammo load carried by the squad by 25%-30% is huge, especially when they're carrying 2,000-3,000 rounds:
Moreover, a squad equipped with with 6.5 mm weapons could take on one equipped with 7.62 mm and outrange them while the latter would run out of ammo sooner. That's what I call overmatch.
It doesn't take rocket science to do this. I'd like to see Bill A develop a SuperG.
This is important. It is a hard sell to get Big Army to adopt a calibre that is heavier than 5.56 mm, but if the weight saving versus 7.62 mm approaches 25%-30% then it becomes compelling. This is the challenge of Grendel development: match 7.62 mm close enough for 6.5 mm to replace this larger calibre as well as 5.56 mm, with the added benefits of simplified battlefield logistics, simplified procurement, lower training requirements and lower spare parts costs.
So what to do? There is nothing wrong with the design of the 6.5 mm bullet. For EU armies however, it's OTM construction isn't acceptable. Design a steel-core projectile with the same G7 FF and BC in a FMJ design that yaws rapidly in soft tissue and you'll be able to pierce level III and IV body armour, which NATO 7.62 M80 ball and NATO 5.56 mm M855 / SS109 presently struggle to do at longer ranges - then you're in business. The present 6.5 mm bullet often doesn't yaw quick enough. The bullet also needs a cannelure to ensure reliable operation in machine guns. Cannelures aren't very good for aerodynamic efficiency. So a military spec 6.5 mm bullet is likely to lose energy more rapidly than its civilian OTM counterpart. Let's not forget that mass-produced military ammo is generally less good than match quality ammo.
This brings us to job two. I believe the Grendel case needs to extended by 10%-15% to give it the extra powder capacity to to get it to MV of around 900 mps when fired from 16" barrels - entirely possible with a 7 g bullet. This results in a cartridge that is identical to what we have now but is slightly longer at around 64 mm. This would very similar to the 6 mm SAW round of the 1970s except for the fact that the calibre is slightly larger. Give the case a less pronounced shoulder to aid MG feeding and extraction and you make it even better.
The big issue here is that as soon as you extend the cartridge length, you need an AR10 platform not an AR15 platform. Since current Grendel weapons are close to the limit of the AR15's limits, that might not be a bad thing. Let's not forget that military shooting can be much more testing on a weapon's components than shooting foxes in your back yard. A heavier weapon also helps mitigate felt recoil, but the overall weight should be somewhere between an AR15 and an AR10, say 3.8 kgs. In a machine gun, however the weight saving would be considerable. A 7.62 mm Minimi converted to 6.5 mm could weigh less than 8 kg. Compared to an 11-12 kg MAG 58 GPMG in 7.62 mm and that's very worthwhile. And let's not forget, reducing the MG ammo load carried by the squad by 25%-30% is huge, especially when they're carrying 2,000-3,000 rounds:
Moreover, a squad equipped with with 6.5 mm weapons could take on one equipped with 7.62 mm and outrange them while the latter would run out of ammo sooner. That's what I call overmatch.
It doesn't take rocket science to do this. I'd like to see Bill A develop a SuperG.