05-10-2011, 12:42 PM
LR1955 Wrote:Joe:There is also a difference between penetrating hard armour - which, given equal bullet construction, is largely determined by the impact energy per square millimetre (i.e. velocity squared x mass) - and ploughing through thickness of softer material like breezeblock in which momentum (velocity x mass) becomes more important.
There is a problem in defining a barrier based on a steel of any sort. Barriers are not monolithic (if that is the word to use). For example, we had to stop using RHA plate as a testing material when armor started to become laminates of different types and alloys of things.
Quote:What you guys need to do is to define the barriers that you require penetration. One of them will be some level of body armor as that stuff is appearing more regularly. Another will be sheet metal and automotive glass separated by some specific amount of space such as found for car and truck doors. A third may be some type of construction material if any is common throughout the world. Not sure of any others but they must be common throughout the world.I agree with that list - but see below.
Quote:You guys are focusing solely on terminal effects and that is a serious mistake.
So, you have to decide what is more important -- penetration of hard things or terminal effects on humans.
In fairness, I gave equal prominence to barrier penetration in my draft outline spec:
4. To replace the 7.62x51 a new cartridge needs to achieve the following:
- to equal the barrier penetration performance of the 7.62mm M80 in terms of overall penetration of a range of media while maintaining its trajectory ("blind to barriers")
5. To replace the 5.56x45 a new cartridge needs to achieve the following:
- to deliver a substantial improvement at all ranges over the 5.56mm M855 in barrier penetration and trajectory maintenance through barriers
That seems clear enough - whichever barriers you choose, the new bullet has to at least match the 7.62mm M80.