General > Discussion
SMG ammo description
breversa:
I guess it's the word "core" that misled me into thinking it was the INNER part of the bullet, instead of the REAR part.
But still... Why aluminium and not lead for the rear part ? Are ammo designers concerned about lead toxicity in the target's body ? :-P
But I think I know the reason why : it's a matter of density.
A bullet with steel tip and lead core would be too homogenous and may be prone to yaw in flight, while a bullet with steel tip and aluminium core would have its weight shifted to the front, causing the core to "follow" the tip in its flight, acting like a stabilizer.
Lowering the global weight of the bullet will also make it less prone to over-penetrate, as required.
I guess we're done with that mystery aren't we ? :)
Damp Squib:
--- Quote from: "breversa" ---But I think I know the reason why : it's a matter of density.
A bullet with steel tip and lead core would be too homogenous and may be prone to yaw in flight, while a bullet with steel tip and aluminium core would have its weight shifted to the front, causing the core to "follow" the tip in its flight, acting like a stabilizer.
--- End quote ---
Bullets don't yaw in flight, because they are spun by rifling. Long bullets are less stable than short bullets and require a steeper rifling twist, but this is otherwise not an issue when the bullet is in the air.
Long bullets, like the bullets in question, destabilise when they leave the air and enter flesh. This is desirable, the bullet cuts a wider, nasty wound when sideways than when point-on. The military are prohibited from using hollow-point bullets that would similarly make larger wounds (prohibited from use on people, aliens not so much).
Using a long aluminium bullet instead of a short lead bullet is entirely to make it less stable (and cut a broader wound when it spins around). Using a long aluminium bullet instead of a long lead bullet is to make it lighter and faster, with more energy (the subsonic 5.7mm rounds carry perhaps one-quarter of the kinetic energy of the supersonic rounds).
--
DS
breversa:
--- Quote from: "Damp Squib" ---Bullets don't yaw in flight, because they are spun by rifling. Long bullets are less stable than short bullets and require a steeper rifling twist, but this is otherwise not an issue when the bullet is in the air.
--- End quote ---
Yes, they DO yaw (moreless, depending on many factors). I've experimented it enough times when checking my targets after FAMAS rifle shooting : some bullets even impact SIDEWAYS.
--- Quote from: "Damp Squib" ---Long bullets, like the bullets in question, destabilise when they leave the air and enter flesh. This is desirable, the bullet cuts a wider, nasty wound when sideways than when point-on. The military are prohibited from using hollow-point bullets that would similarly make larger wounds (prohibited from use on people, aliens not so much).
--- End quote ---
While it's true that military conventions ban the use of hollowpoint bullets, and that yawing increases the wound channel of a projectile, I doubt that's the reason of the aluminium core. But until we get some facts about it,, we may leave that matter aside for now. :)
--- Quote from: "Damp Squib" ---Using a long aluminium bullet instead of a short lead bullet is entirely to make it less stable (and cut a broader wound when it spins around). Using a long aluminium bullet instead of a long lead bullet is to make it lighter and faster, with more energy (the subsonic 5.7mm rounds carry perhaps one-quarter of the kinetic energy of the supersonic rounds).
--- End quote ---
Are those aluminium-core bullets really longer than lead-core ones ?
But indeed, a lighter bullet can go faster, and since E = 1/2mv² (v = speed), impact with more energy than a heavier but slower one. However, light bullets are more affected by wind and are less precise, and still, one aim of the P90 is to be able to defeat body armor at ranges up to 200m...
DS, do you have any source to your arguments ? I found that debate interesting and would like to know the truth about it. :)
Alex:
--- Quote ---The military are prohibited from using hollow-point bullets that would similarly make larger wounds (prohibited from use on people, aliens not so much).
--- End quote ---
An aquantance of mine from the army told me that a "Manufacturing Defect" (in inverted commas with a wink and a nudge) leaves a small air bubble near the tip of the bullet, which effectively makes it a hollow point upon impact.
so much for rules of engagement.
Stalins Organ:
--- Quote from: "Winter" ---
--- Quote from: "Stalins Organ" ---
As you can see the steel bit is the tip, backed by an aluminium body. this gives the ligtest possible projectile (high velocity) with a hard tip (superior penetration).
To me that would be described as a "steel penetrator on an aluminium projectile", rather than an aluminium "core", which implies the middle is aluminium.
--- End quote ---
No, I don't think you're interpreting it quite rightly. It's the bullet that has a steel penetrator and an aluminium core, which -- as you can see in the cross-section -- it does.
--- End quote ---
I don't understand what the difference is you're highlighting bullet for sorry - I said projectile, which is the same thing.
Breversa wrote:
--- Quote ---Are those aluminium-core bullets really longer than lead-core ones ?
--- End quote ---
No they are not - see the web page I linked to - the homogenous bullet is exactly the same size as the aluminium/steel one.
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