03-17-2011, 03:25 AM
LR1955 Wrote:Tony:
A question for you and this is one of the major issues in this discussion. What would a 6.5 Grendel Ball round be? I can assure you and anyone else that the Army isn't about to use extremely expensive match grade bullets for service ball, even if they function in machineguns which is unlikely due to the thin jackets.
And as importantly, what will its capabilities be in terms of danger space and lethality now that it won't be a very expensive match grade bullet with a relatively high BC. Add in a 16" barrel which further reduces MV and he result is better than a 7.62 X 39 but probably less than a round of issued 5.56.
Gene, I don't think it necessarily follows that a military ball round can't have a high BC. Someone on my own forum (who knows a lot more about the technicalities of bullet design than I do) pointed about that the German 7.92mm heavy ball of WW2 was superbly shaped, with a ballistic coefficient of over .5, yet was churned out by the billion. So while I agree that no military is going to be selecting a match-grade bullet, a ball round which matched the shape and weight of such a bullet shouldn't be far behind.
As it is, the Grendel's 123 grain Scenar overtakes 7.62mm ball in retained energy by about 700 metres and by 1000 metres is clearly ahead, with a flatter trajectory and less wind drift too. Given that what is needed to replace 7.62mm is to match M80 performance at long range, there can afford to be some loss of Grendel performance while still achieving this.
Bullet design is the crucial issue in the success of a long-range intermediate. It has to have low drag, but also yaw rapidly and reliably on impact in order to provide effectiveness against unprotected personnel. If the bullet also has to be lead-free that brings further design headaches...
As far as barrel length is concerned, a general-purpose cartridge really should be used in a general-purpose rifle to get the most out of it. That means the barrel should be long enough to get the most out of the cartridge. Since a general-purpose rifle also needs to be compact for urban fighting, that strongly indicates the bullpup configuration as the optimum solution (although I know most Americans don't agree!). I've considered the pros and cons of bullpups, and ways of tackling their issues, HERE.