05-28-2011, 07:17 AM
The "yaw after 2 inches" criterion I set was to maximise the soft-target effectiveness. It's a question of degree rather than a yes/no issue; 4 inches is better than 5, 3 inches better than 4 and so on. It might be expressed as "early and reliable onset of yaw" in general terms, with threshold and objective figures to aim for: e.g. threshold is that 80% of bullets must commence yaw within 3 inches of penetration, objective is that 90% should do so within 2 inches" or some such wording.
In principle I like the idea of a very aerodynamic jacket with a hardened steel core (with a blunt penetrating point) set back inside the jacket, with either an air space or lightweight plastic tip filler. This should yaw readily on penetration of a soft target and also penetrate hard targets. The main problem would be getting enough weight into the bullet to achieve the ballistic coefficient needed for long-range performance (or, to put it another way, to reach the required weight the bullet would be so long that stabilisation would become an issue). Tungsten is technically the ideal core material which would make all this possible, of course, but for the cost!
There is obviously a trade-off between weight and shape, in that the more aerodynamic the shape, the lighter the bullet can afford to be for any given BC. Maybe we should take a look at the 5.56mm FABRL and the light-alloy and plastic cored CETME bullet designs, and start from there. After all, if the CETME bullets showed a good BC with a light-alloy core, then we should surely be able to do better with a steel core.
In principle I like the idea of a very aerodynamic jacket with a hardened steel core (with a blunt penetrating point) set back inside the jacket, with either an air space or lightweight plastic tip filler. This should yaw readily on penetration of a soft target and also penetrate hard targets. The main problem would be getting enough weight into the bullet to achieve the ballistic coefficient needed for long-range performance (or, to put it another way, to reach the required weight the bullet would be so long that stabilisation would become an issue). Tungsten is technically the ideal core material which would make all this possible, of course, but for the cost!
There is obviously a trade-off between weight and shape, in that the more aerodynamic the shape, the lighter the bullet can afford to be for any given BC. Maybe we should take a look at the 5.56mm FABRL and the light-alloy and plastic cored CETME bullet designs, and start from there. After all, if the CETME bullets showed a good BC with a light-alloy core, then we should surely be able to do better with a steel core.